Copyright
by
Samuel Sandoval Solis
2011
The Dissertation Committee for Samuel Sandoval Solis Certifies that this is the
approved version of the following dissertation:
Water Planning and Management for Large Scale River Basins
Case of Study: the Rio Grande/Rio Bravo Transboundary Basin
Committee:
Daene C. McKinney, Supervisor
Randall J. Charbeneau
David R. Maidment
David J. Eaton
Bryan R. Roberts
Water Planning and Management for Large Scale River Basins
Case of Study: the Rio Grande/Rio Bravo Transboundary Basin
by
Samuel Sandoval Solis, B.S.; M.S.
Dissertation
Presented to the Faculty of the Graduate School of
The University of Texas at Austin
in Partial Fulfillment
of the Requirements
for the Degree of
Doctor of Philosophy
The University of Texas at Austin
August, 2011
Dedication
Dedico esta tesis doctoral a Sil, mi amor, mi esposa, mi alma gemela, mi completo, mi
fuerza, mi aliento, mi pasión; este esfuerzo te lo dedico a ti, agradezco infinitamente tu
amor, paciencia y apoyo durante esta aventura llamada doctorado, ¡lo logramos!
A mis padres Jesús y Alicia, los dos son un ejemplo de vida para mi, los amo con toda mi
alma
Acknowledgements
I would like to express my endless gratitude to my advisor, mentor and friend Dr.
Daene McKinney for his wisdom, guidance, and support throughout my time at The
University of Texas. Dr. McKinney provided me with the opportunity to venture into the
fascinating field of water planning and management, transboundary basins and of course
the Rio Grande/Rio Bravo, the basin that made us do research together, try to understand
the incomprehensible (or at least look for some sense), do some traveling and have some
successes and failures during the process; thank you for never made things easy, thank
you for the discussions and insightful talks. I would like to thank Dr. David Maidment,
Dr. Randall Charbeneau, Dr. David Eaton and Dr. Bryan Roberts for being members of
my dissertation committee and for their word of encouragement along the way.
Special thanks to Carlos Patiño Gomez who shared his knowledge regarding the
Rio Grande/Bravo and who helped me and my wife to establish in Austin, I will never
forget his hospitality when we arrived, I appreciate his friendship. Also special thanks to
Becky (Dr. Rebecca Lynn Teasley), she encouraged me to learn about the basin and
modeling, we worked together in the same projects and become excellent friends, I am
thankful for her support, expertise and friendship. In the last few years I have developed a
nice friendship with Eusebio Ingol Blanco, he had become a person to talk and discuss
not only things related with the Rio Grande/Bravo and climate change, but also other
topics such as life, family, Latin America, among other stuff, I appreciate his friendship.
Special thanks are also given to my primary sponsorship CONACyT (Consejo
Nacional de Ciencia y Tecnologia); this Mexican institution provided me all the financial
v
resources during my PhD process, my endless gratitude with CONACYT. Also, partial
funding was provided by U.S. Department of Agriculture, Instituto Mexicano de
Tecnología del Agua (IMTA) and the World Wildlife Fund Chihuahuan Desert Program.
Special thanks to Gregory Thomas from the Natural Heritage Institute who become an
extraordinary friend of adventures as well as my external adviser in hydro-politics and
decision making. Thanks to Hector Arias, he was also part of the outreach of results. Also
special thanks to Jack Sieber and David Yates for their support using WEAP.
In this process I meet a lot of people from both countries, this is a list of people
related to the Rio Grande/Bravo that helped me during my research and later some of
them become friends; excuses in advance if I forget any person; from IMTA: Dr.
Polioptro Martinez, Hector San Vicente, Alberto Guitron; from CONAGUA: Alfredo
Galindo, Vicente Quezada, Doroteo Treviño, Amalio Cardona, Melchor Lopez, Mario
Lopez, Rafael Rosales; from JCAS Chihuahua: Humberto Silva, from CILA: Dr. Roberto
Salmon, Ramiro Lujan, Aldo Garcia, Gilberto Elizalde; from IBWC: Gilbert Anaya,
Elizabeth Verdecchia; from TCEQ: Carlos Rubinstein, Stephen Niemeyer, Kelly Keel;
and from TWDB: Mark Wenzel.
Very special thanks to the “Scientific International Committee for Environmental
flows in the Big Bend”, this is a high qualified scientific group that has become a nice
circle where I have explored environmental policies and learned how to see things from
different perspectives. I would like to give the thanks from USU: Jack Schmidt, David
Dean; from WWF: Mark Briggs, Jurgen Hoth, Mauricio de la Maza, Alfredo Rodriguez,
Amanda Cleghorn, Ivonne Muñoz, Norma Mendiola; from NPS: Jeffery Bennett,
Raymond Skiles, Joe Sirotnak, from Env. Defense: Karen Chapman, from US FWS:
Aimee Roberson, from CONANP: Carlos Sifuentes, and the rest of this amazing group.
vi
Also I created an amazing group of friends that made my life at UT quite
enjoyable, thanks to Bradley Eck, Eric Hersh, Stephanie Johnson and Angela Ronay,
Paula Kulis, Ernest To, Shipeng Fu, Marcelo Somos, Fernando Salas, Dr. Pepe Salas,
Laura Read, Fernando Almada, Natalia Ibañez, Hector Garcia, Sedat Yalcinkaya,
Georges Comair, Gonzalo Espinoza, Benjamin Reith, Sardorbek Musayev among others.
I am grateful for my friends Ryan Schmidt, Denise Landeros, Maria Elena Sanchez, Juan
Carlos Novela, Mayra Meléndez, Giovanni Sosa, Carolina Lopez Espinosa and Javier
Dorantes Perdomo.
Agradezco el apoyo, comprensión y amor de Sil, ella ha sido el pilar mas
importante en este proceso de doctorado, gracias por escuchar mis inquietudes, éxitos y
tropiezos, nada de esto hubiera sido posible sin ti. Te admiro mucho, gracias por estar a
mi lado, gracias por ayudarme durante los momentos difíciles, gracias por soñar juntos.
Agradezco especialmente a mis padres, Jesús y Alicia, por sus palabras de aliento,
oraciones y apoyo, gracias por acompañarme durante mis múltiples visitas a México,
siempre estuvieron en mis pensamientos a lo largo de este proceso, los dos son mis
héroes, los quiero mucho. Gracias a mi Padrinovich y Madrinovich, Gonzalo Sandoval y
María Antonia Muñoz respectivamente, gracias por escucharme, brindarme ánimos y
consejos a lo largo de mi doctorado, gracias por formar parte de nuestra familia.
Agradezco a Elvia Zamora por su apoyo, sus palabras de aliento, su compañía y consejos,
gracias por sus visitas frecuentes a Austin, cada visita nos trajo vitalidad a nuestras vidas.
Este trabajo es también en memoria de Miguel Almaraz Ovando y Álvaro Isidro
Sandoval Sánchez, dos entrañables personas que extraño mucho.
vii
Water Planning and Management for Large Scale River Basins
Case of Study: the Rio Grande/Rio Bravo Transboundary Basin
Publication No._____________
Samuel Sandoval Solis, Ph.D.
The University of Texas at Austin, 2011
Supervisor: Daene C. McKinney
Because water is not equitably distributed in time and place, in the right quantity
with the adequate quality, water planning and management is used to redistribute the
resource in such a way that tries to satisfy the necessities of water users, including the
environment. Policies are proposed to improve the water management, however,
selecting the best alternative can be difficult when tradeoffs among alternatives improve
certain aspects of the planning and management and worsen others. This research
establishes a methodology to evaluate water management policies in order to clearly and
systematically identify policies that improve the water management. First, each water
user, system or environmental requirement are evaluated using performance criteria.
Second, performance criteria are summarized using the Sustainability Index. Finally,
individual Sustainability Indices are grouped using the Sustainability by Group Index.
The Sustainability by Group Index makes it possible to compare groups of water users
and regions at a glance. This methodology has been successfully applied in the Rio
Grande/Rio Bravo basin, a transboundary basin between the United States and Mexico. A
viii
set of scenarios was defined by water users, authorities and environmental organizations
of the basin from both countries. A water resources planning model was constructed to
represent the water management of the basin. The model was used to evaluate several
scenarios and the benefits or damages that each policy provides. Two winning scenarios
(called Meta-scenarios) that improve the management for water users, the environment
and international treaty obligations were identified. Meta-scenario A is an immediate
action scenario that includes: buyback of water rights, improvement in irrigation
infrastructure, water demand reduction for irrigation districts in Mexico and the US,
groundwater banking and the inclusion of environmental flows. Meta-scenario B is a
short term scenario that includes the policies of Meta-scenario A plus expanded buyback
of water rights, additional improvements in infrastructure and sharing of water savings
between farmers in the US and Mexico. Results have been presented to decision makers
and water users in both countries who will ultimately decide if they should implement the
suggested policies. Most importantly, some alternative policies are now known that can
help to improve the water management in the basin, for whom and where.
ix
Table of Contents
List of Tables ....................................................................................................... xiv List of Figures ...................................................................................................... xvi Chapter 1 Introduction .............................................................................................1 1.1 Background ...............................................................................................1 1.2 Objectives .................................................................................................2 1.3 Dissertation Outline ..................................................................................2 1.4 Contributions to the State of the Art .........................................................3 Chapter 2 Literature Review ....................................................................................6 2.1 Water Planning and Management .............................................................6 2.1.1 Transboundary Water Planning and Management ......................10 2.1.2 Sustainable Water Resources Systems........................................13 2.1.3 Integrated Water Resources Management (IWRM) ...................14 2.1.4 Decision Support Systems (DSS) ...............................................16 2.2 Rio Grande/Rio Bravo Basin ..................................................................19 2.2.1 Introduction .................................................................................19 2.2.2 Background .................................................................................21 2.2.2.1 Convention of 1906.........................................................23 2.2.2.2 Treaty of 1944 .................................................................25 2.2.2.3 After Treaties era ............................................................27 2.2.3 Challenges ...................................................................................30 2.2.3.1 Planning and management ..............................................30 2.2.3.2 Water Quality ..................................................................37 2.2.3.3 Environment ....................................................................37 2.2.4 Current Status..............................................................................43 Chapter 3 Methodology .........................................................................................48 3.1 Performance Criteria ...............................................................................48 3.1.1 Reliability ....................................................................................49 x
3.1.2 Resilience ....................................................................................50 3.1.3 Vulnerability ...............................................................................50 3.1.4 Maximum Deficit ........................................................................51 3.1.5 Standard Deviation......................................................................51 3.2 Sustainability Index ................................................................................52 3.2.1 By User .......................................................................................53 3.2.2 By Group .....................................................................................56 3.3 Integration of Results ..............................................................................58 Chapter 4 Application: Rio Grande/Rio Bravo Basin............................................60 4.1 International Agreements ........................................................................60 4.1.1 Convention of 1906.....................................................................60 4.1.2 Treaty of 1944 .............................................................................61 4.2 Mexico ....................................................................................................63 4.3 United States ...........................................................................................64 4.4 Environment ............................................................................................66 Chapter 5 Water Resources Planning Model .........................................................68 5.1 Introduction .............................................................................................68 5.2 Period of Analysis ...................................................................................69 5.3 Hydrologic Data ......................................................................................69 5.4 Water Demands .......................................................................................70 5.5 Infrastructure ...........................................................................................72 5.6 Operation.................................................................................................72 5.7 Model Testing .........................................................................................73 5.7.1 Calibration...................................................................................73 5.7.2 Validation....................................................................................74 Chapter 6 Water Management Scenarios ...............................................................80 6.1 Baseline Scenario ....................................................................................80 6.2 Upper Basin Scenarios: Rio Conchos Sub-basin ....................................81 6.2.1 PADUA Program ........................................................................81 xi
6.2.2 Reduction of DR-005 Delicias to 50,000 hectares......................83 6.2.3 IBWC Minute 309.......................................................................85 6.2.4 In Lieu Groundwater Banking in the Rio Conchos ....................87 6.2.5 Environmental Flows ..................................................................93 6.3 Lower basin: the Lower Rio Grande Valley ...........................................98 6.3.1 Reduction in water allocation for the Water Master Sections ....98 6.3.2 Buy Back of Water Rights in DR-025 Bajo Rio Bravo ............100 6.3.3 Improvement in Infrastructure at DR-025 Bajo Rio Bravo ......102 6.4 Current Scenario ...................................................................................104 Chapter 7 Scenarios Results.................................................................................105 7.1 Scenarios ...............................................................................................105 7.1.2 Results by User .........................................................................107 7.1.2.1 DR-005 Delicias............................................................107 7.1.2.2 DR-025 Bajo Rio Bravo................................................109 7.1.2.3 Water Master Section 8-13 ...........................................111 7.1.2.4 Treaty Obligations ........................................................113 7.1.2.5 Environment ..................................................................115 7.1.3 Results by Group.......................................................................116 7.1.3.1 Rio Grande/Rio Bravo ..................................................117 7.1.3.2 United States .................................................................118 7.1.3.3 Mexico ..........................................................................119 7.1.3.4 Environment ..................................................................120 7.1.4 Summary of Results ..................................................................121 Chapter 8 Meta-scenarios Results ........................................................................123 8.1 Definition ..............................................................................................123 8.2 Results by User .....................................................................................128 8.2.1 DR-005 Delicias, DR-025 Bajo Rio Bravo and WMS 8-13 .....128 8.2.2 Treaty Obligations ....................................................................131 8.2.3 Environment ..............................................................................132 8.3 Results by Group...................................................................................134 xii
8.3.1 Rio Grande/Rio Bravo ..............................................................135 8.3.2 United States and Mexico .........................................................136 8.3.3 Environment ..............................................................................137 8.4 Results by Region .................................................................................138 8.4.1 Baseline and Current Scenarios ................................................138 8.4.2 Meta-Scenarios .........................................................................142 8.5 Summary of Results ..............................................................................148 Chapter 9 Conclusions .........................................................................................152 9.1 Aim of the Dissertation .........................................................................152 9.2 Discussion .............................................................................................152 9.3 Conclusions ...........................................................................................162 9.4 Recommendations .................................................................................164 9.5 Future Work ..........................................................................................165 References ............................................................................................................167 VITA ....................................................................................................................185 xiii
List of Tables
Table 2-1: Reliability, Resilience and Vulnerability of the Mexican delivery of water
according to the 1944 Treaty. ...........................................................29
Table 5-1: Water Demands considered in the Rio Grande/Rio Bravo WEAP Model
...........................................................................................................71
Table 6-1: Water Rights Bought Back Under the PADUA Program ....................81
Table 6-2: Investment in the PADUA Program .....................................................83
Table 6-3: Water demands for DR-005 Delicias after reduction of the irrigated area to
50,000 ha. ..........................................................................................84
Table 6-4: Water savings expected after the conclusion of Minute 309................86
Table 6-5: Investment spent in Minute 309 ...........................................................87
Table 6-6: Environmental Flows in the Rio Conchos Basin..................................95
Table 6-7: Estimated investment to buy-back of water rights for DR-025 Bajo Rio
Bravo ...............................................................................................101
Table 6-8: Proposed improvements in the conveyance, application and global
efficiencies for DR-025 Bajo Rio Bravo ........................................103
Table 6-9: Investment to improve the infrastructure in DR-005 Delicias ...........103
Table 7-1: List of scenarios for the Rio Grande/Rio Bravo Basin .......................106
Table 7-2: Sustainability Index for DR-005 Delicias, Baseline and Scenarios ...108
Table 7-3: Sustainability Index for DR-025 Bajo Rio Bravo, Baseline and Scenarios
.........................................................................................................110
Table 7-4: Sustainability Index for WMS 8-13, Baseline and Scenarios ............112
Table 7-5: Sustainability Index for Treaty Obligations, Baseline and Scenarios 114
xiv
Table 7-6: Sustainability Index for environmental control point VMc Camargo,
Baseline and Scenarios ...................................................................115
Table 8-1: Meta-scenarios for the Rio Grande/Rio Bravo Basin .........................126
Table 8-2: Sustainability Index for DR-005, DR-025 and WMS 8-13; Baseline,
Current and Meta-scenarios ............................................................129
Table 8-3: Sustainability Index for Treaty Obligations; Baseline, Current and Metascenarios ..........................................................................................131
Table 8-4: Sustainability Index for Environmental Control points; Baseline, Current
and Meta-scenarios .........................................................................133
Table 8-5: Relative Sustainability per region; Baseline and Current scenarios...138
Table 8-6: Change in the Sustainability per group; Baseline and Current scenarios139
Table 8-7: Relative Sustainability per region; Current and Meta-scenarios ........142
Table 8-8: Change in the Sustainability per group; Current and Meta-scenarios 142
xv
List of Figures
Figure 1-1: Synthesis of Results and Scenario Analyses .......................................5
Figure 2-1: Transboundary River Basins (Source: Atlas of International Freshwater
Agreements, Wolf 2002) ...................................................................10
Figure 2-2: Water Stress in Transboundary Basins (Source: Atlas of International
Freshwater Agreements, Wolf 2002) ................................................12
Figure 2-3: Rio Grande/Rio Bravo Basin ............................................................20
Figure 2-4: Water consumption in Mexico and the U.S. along the Rio Grande/Rio
Bravo and in Mexican tributaries......................................................33
Figure 2-5: Water Consumption for Mexico 1950-2004 .....................................35
Figure 2-6: Water Consumption for the U.S., 1950-2004 ...................................36
Figure 2-7: Reservoir development in the United States for the Rio Grande/Rio
Bravo .................................................................................................39
Figure 2-8: Reservoir development in Mexico for the Rio Grande/Rio Bravo ...39
Figure 3-1: Performance Criteria Matrix (PCM), Sustainability Index Matrix (SIM)
and Relative Sustainability Matrix (RSM) .......................................59
Figure 5-1: Historic water supply for U.S. demands ...........................................75
Figure 5-2: Historic water supply for Mexican demands ....................................76
Figure 5-3: U.S. storage in the international dams; Model versus Historic.........77
Figure 5-4: Mexican storage in the international dams; Model versus Historic ..77
Figure 6-1: Irrigation Districts in the Rio Conchos Basin ...................................82
Figure 6-2: Scheme of the Groundwater Banking through the In Lieu Method..88
Figure 6-3: Scheme of water supply and diversion under the In Lieu groundwater
banking method .................................................................................89
xvi
Figure 6-4: Groundwater banking in the Rio Conchos Basin..............................92
Figure 6-3: Environmental Control Points in the Rio Conchos Sub-basin ..........94
Figure 6-6: TCEQ Water Master Sections ...........................................................99
Figure 6-7: Lower Rio Grande Valley ...............................................................101
Figure 7-1: Sustainability Index and Δ(Criterion) of DR-005 Delicias.............108
Figure 7-2: Sustainability Index and Δ(Criterion) of DR-025 Bajo Rio Bravo.110
Figure 7-3: Sustainability Index and Δ(Criterion) of WMS 8-13 ......................112
Figure 7-4: Sustainability Index and Δ(Criterion) of Treaty Obligations..........114
Figure 7-5: Sustainability Index and Δ(Criterion) of environmental control point
VMc Camargo .................................................................................116
Figure 7-6: Relative Sustainability for the Rio Grande/Rio Bravo ...................117
Figure 7-7: Relative Sustainability for the United States ..................................118
Figure 7-8: Relative Sustainability for Mexico .................................................119
Figure 7-9: Relative Sustainability for Environmental requirements group in the Rio
Conchos sub-basin ..........................................................................120
Figure 8-1: Sustainability Index for DR-005, DR-025 and WMS 8-13; Baseline,
Current and Meta-scenarios ............................................................130
Figure 8-2:
Sustainability Index for Treaty Obligations; Baseline, Current and
Meta-scenarios ................................................................................132
Figure 8-3:
Sustainability Index for all environmental control points in the Conchos
basin; Baseline, Current and Meta-scenarios ..................................134
Figure 8-4:
Relative Sustainability for the Rio Grande/Rio Bravo group; Baseline,
Current and Meta-scenarios ............................................................135
Figure 8-5:
Relative Sustainability for the United States and Mexico water users’
group; Baseline, Current and Meta-scenarios .................................136
xvii
Figure 8-6:
Relative Sustainability for Environmental requirements group; Baseline,
Current and Meta-scenarios ............................................................137
Figure 8-7: Relative Sustainability for regions; Baseline scenario....................139
Figure 8-8: Change in the Relative Sustainability, Current Vs. Baseline scenario140
Figure 8-9: Relative Sustainability for regions; Current Scenario ....................143
Figure 8-10: Change in the Relative Sustainability, Meta-scenario A Vs. Current
Scenario...........................................................................................145
Figure 8-11: Change in the Relative Sustainability, Meta-scenario B Vs. Current
Scenario...........................................................................................147
Figure 9-1: Methodology proposed for results’ analysis ...................................157
xviii
Chapter 1 Introduction
1.1 BACKGROUND
Because water is not equitably distributed in time and place, in the right quantity
with the adequate quality, a discipline called water planning and management is used to
redistribute the resource in a way that satisfies the needs of water users, including the
environment. As a rule, water planning and management tries to meet the water
requirements of all the water users, although, sometimes this is not possible. Frequently,
conflicts among water users arise because water is a shared resource. The difficulties
increase when the systems become large with numerous water users, several types of use,
with unequal spatial distribution and such scarcity that water cannot be re-distributed
without affecting other water users. Nowadays, this seems to be the common pattern of
water allocation in large basins.
In transboundary basins, water planning and management is more complex. When
possible, negotiations take place in order to define the sources, quantity, quality and
timing of water to which each riparian has a right (Dinar et al. 2007). Typically,
international basin commissions integrate country representatives to guarantee
compliance with international agreements. In these basins, international agreements,
local, federal and state regulations must be met, all at the same time. Problems in these
regions arise in the coordination of all authorities, agencies and water users involved in
the planning and management.
Water planning and management involves uncertainty in future events (Loucks
and Van Beek 2005). In order to assess these uncertainties, several tools have been
developed, such as simulation and optimization models. Models represent as accurately
as possible the real water resource systems, but they also provide a tremendous amount of
1
results that are not easy to interpret, especially in large basins. Selecting the best
alternative can be difficult when tradeoffs among alternatives improve certain aspects of
the planning and management and worsen others. It can be difficult to present an
evaluation of a water resources system in a way that makes the selection of the best
alternative easier and clearer.
1.2 OBJECTIVES
The goal of this research is to develop a methodology for evaluating water
management scenarios for a large scale transboundary river basin. The objectives of this
research are:
1.
Construct, calibrate and validate a water resources planning model that represents
the hydro-physical and regulatory framework of a large scale transboundary
basin.
2.
Define a methodology to evaluate and compare water management scenarios.
3.
Utilize the water resources planning model and the methodology defined to
evaluate alternative scenarios for improving water management in the basin.
4.
Assess the water planning and management for the transboundary basin.
1.3 DISSERTATION OUTLINE
This dissertation is divided into nine chapters. The scope and the objectives of the
research are stated in the first chapter. The literature review of water planning and
management in basins, transboundary basins and in the Rio Grande/Rio Bravo basin is
presented in chapter two. Chapter three describes the methodology implemented to
evaluate, summarize and compare results for different water management scenarios.
2
Chapter four describes the water management principles of the Rio Grande/Rio Bravo
basin. Chapter five describes the construction calibration and testing of the water
resources planning model built to simulate the water resources system. In chapter 6 the
alternative water management policies to be evaluated are defined. Chapter seven
presents the results of the scenarios analyzed. Chapter eight shows the results for “Metascenarios”, which are a combination of scenarios that were identified as beneficial for the
water management in the basin. Chapter nine provides the conclusions and
recommendation of this research.
1.4 CONTRIBUTIONS TO THE STATE OF THE ART
This research presents two main contributions to the state of the art:
1. Synthesis of Results –The methodology developed in this research allows
the systematic evaluation of alternative water management policies (scenarios)
for individual water users, groups of water users, regions or a whole basin that
is under consideration. The results are stored and summarized in 3 different
layers for different purposes and audiences. In the first level, Performance
Criteria (Chapter 3.1) are stored for different water users, the environment or
system requirements; in this level it is possible to analyze in detail the effects
of each policy evaluated for each individual water user. In the second level,
the Sustainability Index (Chapter 3.2.1) the results of the performance criteria
are summarized for each water user, system or environmental requirement; in
this level it is easier to compare different water management policies than at
the water user level. Results of the previous two levels are focused on water
users and water operators. In the third level, the Relative Sustainability Index
3
(Chapter 3.2.2) summarizes the results of the Sustainability Index; results are
recapped by water users groups, regions and for the whole basin. In this level
it is easier to compare different water management policies from the
perspective of a water user’s group, a region or the whole basin. Results from
this level make it possible to identify areas of potential improvement and
regions at risk. Results from this level are focused on water authorities and
decision makers.
2. Analysis of Scenarios – The analysis of scenario evaluation results allows the
systematic identification of policies that improve water management in the
basin. This analysis is done in two steps. In the first step, individual or basic
combinations of Scenarios (Chapter 7) are evaluated to identify their effects,
quantify the magnitude of the benefits or drawbacks, and locate the areas of
improvement or worsening; during this step the benefits and drawbacks for
water users, the system and environmental requirements are identified. In the
second step, the policies that provided more benefits are integrated into Metascenarios (Chapter 8), which are individual or combination of policies that
provide additional mutual benefits for water users, system and environmental
requirements than the individual scenarios.
These two contributions are graphically represented in Figure 1-1. Similar studies
have analyzed a wide range of performance criteria without synthesizing results to
identifying winning policies, such as average storage and releases (Vigerstol 2002, MRC
2004), total volume of water supplied to water users and to the treaty obligations (OriveAlba 1945, Vigerstol 2002, Tate 2002, Gastelum et al. 2009), water supply in drought
and normal conditions (Tate 2002), irrigated area (Gastelum et al. 2009, MRC 2004),
minimum delivery, average annual supply, vulnerability and resilience (Teasley 2009)
4
and reliability (Tate 2002, MRC 2004, Gastelum et al. 2009, Teasley 2009). Gastelum et
al. (2009) and Teasley (2009) summarized their results in terms of monetary value and
coalition value, respectively; however, none of the previous studies considered
performance criteria to systematically synthesize the evaluation of benefits and the
drawbacks for scenarios in order to assess, identify and construct policies that improve
the water management in the basin.
Figure 1-1: Synthesis of Results and Scenario Analyses
5
Chapter 2 Literature Review
In this chapter is presented the literature review of water planning and
management in general, for transboundary basins and in the Rio Grande/Rio Bravo basin.
The first section describes the literature review of water planning and management,
sustainable water resource systems, integrated water resource management and decision
support systems. The second section focuses in the Rio Grande/Rio Bravo planning and
management; how it has evolved along time, challenges and current status of the basin.
2.1 WATER PLANNING AND MANAGEMENT
Too little, too much and too polluted water (Loucks 1981), too much ecosystem
lost; these are the motivations of water planning and management. Reducing the adverse
impacts of droughts, floods, excessive pollution and environmental degradation are the
objectives of several planning and management exercises. Other goals include increasing
water supply, hydropower, improving recreation, navigation and current policies to
obtain more benefits. Finding the best social, economical and environmental way to
manage the renewable yet finite and variable water resource, today and in the future, is
the highest premise of water planning and management, in other words, designing
sustainable water resources systems.
Water resources systems are integrated by the interaction between: (1) the natural
hydrology, (2) the human development in the basin and (3) the legal/regulation system to
administrate this resource. Basin’s natural hydrology include: precipitation, evaporation,
infiltration, runoff, rivers, lakes, aquifers, flood plains, deltas, estuaries, watersheds, soils,
vegetation, fauna, ecosystems, geomorphology, geology, among others characteristics.
Human development in the basin include: reservoirs, channels, infrastructure, water
supply facilities, sewage systems, discharges, water treatment plants, irrigation districts,
6
return flows, hydropower, pumps plants, recreation facilities, levees, flooding control
facilities, among other facilities. The administrative system include: regulations, laws,
operation and allocation rules, compacts, treaties, agreements and conventions, between
water users, institutions, states, nations and the environment. Humankind use water to
satisfy its requirements for consumption, food production, industry, recreation, energy
production, health and sanitary purposes. How to meet human water requirements
without compromising the environmental health of the ecosystems considering the
current and future water availability in the basin? Water planning and management is a
discipline that analyzes, proposes strategies and designs sustainable water resources
systems to answer the previous question, in a broad sense, it deals with problems of water
quantity and quality in basins.
Water quantity problems refer to challenges along the whole spectrum of
hydrologic conditions: droughts, normal conditions and flooding. Drought problems are
related to periods of water scarcity; how to operate the system to reduce, to the extent of
possible, the negative effects on human and environmental requirements in dry periods?
During normal hydrologic condition, problems are related to water allocation and system
operation; how much water can be allocated to each stakeholder to obtain the most
benefits without compromising the ecosystems’ environmental health and the future
availability of water? Flooding problems are related to the excess of water during short
periods of time, which facilities and what strategies are needed to avoid damage for a
determined flood event? Water quantity problems refer to issues related to intolerable
water quality conditions for determined use, what kind of facilities and strategies are
necessary to satisfy the water quality necessary to met environmental and human water
requirements?
7
Several methodologies, philosophies and mathematical models have been
proposed to address these questions. In some sense, these procedures represent the value
that the society, governments, politicians, scientist and engineers gave to water,
considering the social, economic and political context. In the 1800’s and early 1900’s,
water planning and management was focused in designing systems that maximize the use
of water and provide the most economic benefits for water users, while following the
interests and vision of the respective country, agency or ministry. For instance, the
objective of the water negotiations in the treaty of 1944 between the U.S. and Mexico
was to maximize the use of water for agriculture purposes while providing an equitable
allocation of water between both nations in the Colorado River and the Rio Grande/Rio
Bravo (Enriquez-Coyro 1976, Orive-Alba 1945, Samaniego-López 2004). Primarily,
water systems were designed to meet single purpose systems, agriculture and hydropower
were the most common objective for systems designing. Development in the system was
justifiable when the estimated cost was lower than the estimated benefits (USBR 1949).
Later, systems started becoming more complex because constraints were imposed by
existing law, international and interstate agreements, and the change from single to multipurpose water systems. Typically, potential water uses considered were: irrigation,
municipal and industrial, hydropower, flood control, minimum flow for navigation,
recreational use and useful aquatic life (Maass et al. 1966). Given the new multi-purpose
nature of the systems, research and study cases were necessary to determine water
allocation that provided the most economic benefits; for instance the Tennessee Valley
Authority case of study was the first large scale multipurpose river development
(Ransmeier 1942).
In the 1960’s, water planning and management focused in finding the design
(infrastructure and operation policies) that maximize the net benefits of the system (Total
8
Cost – Total Benefits); in other words, the solution that provided the most economic
benefits must be the executive design. Design of water resources systems were divided in
four steps: identifying the objectives for the system, translating these objectives into
design criteria (equations), propose several plans (scenarios) and evaluate the outcome
for each of the plans. All scenarios were compared and the scenario that provided most
net benefits was selected (Maass et al. 1966). In some sense, this philosophy considered
the economic benefits as the driver of water systems’ design, water users, authorities,
decision makers and the environment must obey the outcome of this economic analysis.
Some of the problems from the previous approach are: (1) not all benefits or cost can be
easily expressed in economic terms, the most significant example is the cost/benefit of
environmental degradation/conservation; (2) legal/regulatory constraints must be taken
into account and not ignored for the sake of maximum economic net benefit, and (3) it is
important who pays and receives the benefits; water users, decision makers and the
environment matter (Loucks et al 1981).
In the 1980’s Loucks et al. (1981) saw the water planning and management as a
discipline that goes beyond the economic value of a system; water systems are influenced
also by social, environmental, and political (institutional) objectives. By this time,
authorities, water users, society, conservationist and politicians took a more active role in
the planning process. Water resources engineers change their role from water planning
dictators to a more democratic position, they were in charge of hearing, understanding
and addressing (to the extent of possible ) the necessities of different groups, and then
presenting a set of best decisions to a water planning council, where decision are made.
This approach revolutionized water planning and management philosophy, from finding
the maximum net benefit, to identifying best feasible decisions (policies) given the social,
9
economical, environmental and political (institutional) requirements, considering the
natural and legal restrictions of the system (Loucks and van Beek 2005).
2.1.1 Transboundary Water Planning and Management
About 60% of the global freshwater flow is generated in 263 international river
basins (Figure 2-1); these transboundary basins cover nearly one half of the of the earth’s
land surface where over forty percent of the world’s population live (Giordano and Wolf
2002, UN 1978). Water management in transboundary basins is more complex; it is more
difficult to identify the best water management that balance human and environmental
requirements when there are interests of several nations; and concepts of sovereignty
(Harmon 1895), cooperation and equity (Oppenheim 1928, Bogardus 1964),
appropriative or riparian water rights (Burnes and Quirk 1979) are considered and
discussed during the water planning process.
Figure 2-1: Transboundary River Basins (Source: Atlas of International Freshwater
Agreements, Wolf 2002)
10
Sovereignty is a concept regarding the unrestricted exploitation of nation’s natural
resources, including water, within its own territory (Harmon 1895). This concept has
been attempted/used in transboundary basins during unilateral actions in water
developments projects. For instance, unilateral actions of Turkey have affected Syria and
Iraq; the Great Anatolia Project undertaken by Turkey have used and diminished the
streamflow for both downstream countries (Lupu 2002, Czekanski 2005). On the
contrary, cooperation and equity are concepts regarding the necessity to set common
ground and allocate water between nations fairly and reasonably (Dinar et al. 2007), for
instance, the treaty of 1944 between the U.S. and Mexico shows the spirit of both nations
to reasonably and fairly allocate the waters of the Rio Grande/Rio Bravo, Colorado and
Tijuana rivers (Enriquez-Coyro 1976, Samaniego-Lopez 2004).
In addition, nations have argued appropriative water rights, “first in time, first in
right”, claiming the long usage of river’s water before other riparian nations and as a
consequence, the right to use the same amount of water in the future in spite of the harm
this can cause in the economic development of upstream riparian countries. For instance,
Egypt used its water right seniority in the Nile River during negotiations of the 1929 Nile
Waters Treaty (Nile 1929), the 1959 Nile Waters Agreement (Nile 1959) and lately in the
Nile Basin Initiative (NBI 2002). On the other hand, nations have argued riparian water
rights (Enriquez-Coyro 1976); claiming that each riparian country has the right to take
water for reasonable use regardless of the location in the basin (upstream or downstream),
i.e. Ethiopia has claimed this concept in the Nile river, given that the Blue Nile that
originates in this country provide about 85% of the water flowing into Egypt (Dinar et al.
2007).
Another catalyst for water conflicts and agreements is the natural water scarcity of
transboundary basins. In the Rio Grande/Rio Bravo, the scarcity of water in the 1880’s
11
and 1890’s derived in the 1906 Convention between the U.S. and Mexico, which is an
agreement to allocate water in the El Paso/Ciudad Juarez valley. Dinar and Dinar (2005)
showed that in two-riparian basins, scarcity is the key issue that drives the cooperation
process. Figure 2-2 shows the water stress in transboundary basins (Wolf 2002), the Rio
Grande/Bravo Basin is one of the most stressed basins in the world, less than 500 cubic
meters are available per person per year.
Figure 2-2: Water Stress in Transboundary Basins (Source: Atlas of International
Freshwater Agreements, Wolf 2002)
In order to provide guidance and to avoid conflicts between nations, the
international community has developed principles for transboundary water resources. In
1966, the Helsinki rules outline the basic principles for an equitable utilization of water in
international rivers and the commitment not to cause any harm to basin states (ILA
1966). In 1997, the United Nation Convention on the law of the non-navigational uses of
12
international watercourses (UN 1997) further defined the concepts of “equitable and
reasonable utilization and participation” of international water courses as well as the
“obligation not to cause significant harm” that were undefined on the Helsinki rules. In
addition, regional agreements provide guidance in international water share and
management. The European Union agreed two conventions: (1) the convention on
environmental impact assessment in a transboundary context (UNECE 1991), in order to
prevent adverse ecosystem’s impact between riparian nations, and (2) the convention on
the protection and use of transboundary water courses and international lakes (UNECE
1992), this agreement provide further provisions for monitoring, research assistance and
water management protecting basin’s ecosystems. Similarly, the Southern African
Development Community agreed the protocol on shared watercourse (SADC 2000), this
protocol is a regional adaptation of the UN Convention (UN 1997).
2.1.2 Sustainable Water Resources Systems
It has been 30 years since the concept of “Sustainable development” was for the
first time introduced by the World Conservation Strategy (IUCN 1980). Sustainable
development balances the exploitation of the natural resources, technology development
and institutional change, in order to enhance the potential to meet human needs and
aspirations, now and in the future (WCED 1987). Loucks (1997) defined sustainable
water resources systems as “those systems designed and managed to contribute fully to
the objectives of society, now and in the future, while maintaining their ecological,
environmental and hydrological integrity.”
Part of the complexity of the sustainability concept lies in the uncertainty of: (1)
necessities, wishes and requirements of future’s society; and (2) future climate conditions
and thus, future basin’s hydrology. The only certain about future is a constant change in
13
climate conditions and water requirements (IPCC 2007a). How to deal with this
uncertainty? According to IPCC (2007b), system’s adaptation is key to deal with this
uncertainties; it is necessary to define adaptive policies that are flexible enough to supply
more frequently water requirements (more reliable), reducing deficits in water supply
(less vulnerable) and recovering faster from deficits (more resilient) given a change in
climate conditions (Bates et al. 2008, Brekke at al. 2009). Adaptive management policies
are those strategies designed to adjust to changing conditions given new information in
water requirements or forecasting of future climate conditions. Thus, Sustainable water
resources are those systems designed and operated using adaptive policies that make the
system more reliable and resilient, less vulnerable, considering uncertainty in future
climate conditions and water requirements. Because of this, the sustainability of a basin
is also a measure of its adaptive capacity to current and future conditions.
2.1.3 Integrated Water Resources Management (IWRM)
The concept of Integrated Water Resources Management (IWRM) started
appearing in the 80’s (Biswas 1981) and it has been evolving primarily as a consequence
of two conditions: (1) an increasing pressure on water resources caused by growing
population and energy requirements, socio-economic developments, and environmental
protection; and (2) designing of water resources systems migrated from a centralized,
supply-oriented and engineer-bias approach, to an inclusive multi-sectoral, demandoriented and multi-disciplinary approach, often called integrated water resources
management (Loucks and van Beek 2005).
According to the Global Water Partnership (GWP 2000), “IWRM is a process
which promotes the coordinated development on management of water, land and other
related resources, in order to maximize the resultant economic and social welfare in an
14
equitable manner without compromising the sustainability of vital ecosystems.” This
process must be a participatory exercise involving water users, planners, NGO’s,
scientist, operators and decision makers at all levels, the aim is to consider all
perspectives and ideas during the definition of the water management. Consequently,
everybody included in this process feels important part during the definition, operation
and evaluation of water management policies.
The objectives of IWRM include: (1) provide a forum where all people and
institutions involved in water management can express and hear other’s opinions, express
concerns, complaints and solutions regarding this share resource, making water
management a more transparent and inclusive process, (2) establish what is the definition
of “sustainable water resource system” for the basin, what are the objectives to achieve?
(3) define laws, regulations and rules to allocate water, establish priorities, protect the
environment according to the objectives defined; (4) provide mechanisms to evaluate and
modify (if necessary) current and future water management of the basin, making water
planning and management a continuous adaptive process.
Let’s define the relation between sustainable water resources systems, adaptive
policies and integrated water resources management (IWRM). Designing sustainable
water resources system is the highest premise in water planning and management; in
order to achieve this goal it is necessary to identify adaptive policies that deals with
different climate conditions and changing water demands. Basin models are used to
simulate water resources systems, considering the natural hydrology, human development
and the administrative water allocation system in the basin. Models are used to test
different policies, they help in determining adaptive policies; which policies, or
combinations of those, are necessary to make the system sustainable: more reliable and
resilient, and less vulnerable, compared to the current system. Integrated water resources
15
management is the process of bringing together all the people involved in the water
management of the basin (water users, authorities, scientist, environmentalist and
decision makers) to discuss and define what is the meaning of “sustainable water
resource system“ for the basin; in other words, what are the goals to achieve. These goals
include benefits for the economy, environment and society. For each of these goals, a
series of performance criteria is necessary to evaluate and compare different water
management policies. Several adaptive policies may reach the goals established in the
definition of “sustainable water resource system”; during the IWRM process it is selected
which of these policies should be chosen based on a consensus among the people
included in the IWRM process. Notice that during the IWRM process is considered at all
times the necessity to improve the welfare of society and the water resource system.
2.1.4 Decision Support Systems (DSS)
Nowadays, it is acknowledge the relationship between decision-making and the
society’s potential improvements/worsening in their economy and quality of life, as well
as environmental degradation/conservation. Decisions making in water management
affect the environment, economy and social welfare of the people inside and outside the
basin; water users upstream and downstream; water quantity, quality and its seasonal
distribution; water
storage in reservoirs and aquifers; surface and groundwater
availability; among others aspects. Any proposed policy will have consequences in water
supply for the rest of water users; thus, it is necessary to consider the environment and
include stakeholders during the decision making process because they must negotiated
their requests and compromise with the agreements taken (Loucks and van Beek 2005).
During the planning, management and decision making process, it is useful to know the
consequences of possible decisions to be made (Georgakakos and Martin 1996). This
16
information is valuable to those responsible for choosing the best decision; it helps the
understanding of expected outcomes of the decisions taken. DSS are interactive
mathematical and computational models that represent the natural system whose
objective is to quantify, evaluate and compare the benefits and worsening of different
water management policies (Labadie and Sullivan 1986).
DSS do not solve the problem of finding the “best management” by themselves;
they are tools that facilitate the evaluation of different management policies and their
consequences; DSS help the understanding of different strategies and their outcomes.
Ultimately, decision makers will decide the water management of the system considering
the information provided by the DSS. Also, it is not enough to properly represent the
natural and regulatory systems to administer water through DSS; results must be
presented to people involved in the planning and management process, when solutions
are needed, in an adequate format, accessible and understandable to these people and the
community. DSS should provide a set of solutions during the window of opportunity
when there is an interest in determined issue; if not, results will not have any impact in
water management (Loucks and Da Costa 1991). Additionally, decision makers and
water users should have confidence and trust in DSS results. For this purpose, it is
necessary a close relation between the modeler, decision makers and water users during
the DSS construction. Participation, supervision and feedback from the people involved
in the water management process are needed to built trust and confidence on the DSS and
its results, this exercise provide a shared vision of how the water system works.
DSS can be a single or multiple systems, all of them integrated by using an
interface that allows the interaction between the user(s) and system(s). DSS can be
integrated by the following systems: a) measurement, for instance remote sensing and in
situ measurements; b) information, including geographic information systems and
17
databases; c) models, such as economic, hydrologic, planning, optimization, holistic,
empiric models; and d) analysis, such as evaluation, performance and diagnostic tools
(Loucks and van Beek 2005).
Because of the improvements in computer calculation capacity in the last two
decades, DSS have been used more frequently to represent water systems and evaluate
alternative water management policies. Programs such as AQUATOOL (Andreu et al.
1996), RIBASIM (Delft Hydraulics 2004), MIKE-BASIN (DHI 1997), MODSIM-DSS
(CSU 2011), OASIS (HydroLogics 2009), RIVERWARE (Zagona et al. 1998), WRAP
(Wurbs 2005), STELLA (Palmer 2010), WEAP (Raskin et al. 2001, Yates et al. 2005a
and 2005b); among others, have been used as the foundation of DSS in different basins.
DSS have been constructed for several transboundary basins; in America for the
Colorado river (Schuster 1989, Gilmore et al. 2000), Rio Grande (Vigerstol 2002, Tate
2002, Brandes 2004, Danner et al. 2006, Teasley 2009), Columbia (Dufournaud 1982,
Rogers 1991) and Red River (Simonovic 1999); in Asia for the Mekong (Dufournaud
1982, Baran and Coates 2000, MRC 2004), Ganges-Brahmaputra (Rogers 1993, Salewicz
and Nakayama 2004), Amu Darya and Syr Darya rivers (Raskin et al. 1992, Savoskul et
al. 2003, Teasley and McKinney 2011); in Africa for the Nile (Rogers 1969, 1991 and
1993, Georgakakos 2007), Congo (McCartney 2007), Zambezi (Salewicz 1991), Volta
(De Condappa et al. 2009) and Okavango (EPSMO-BIOKAVANGO Eflows Team
2009); in Europe for the Danube (Salewicz 1991, Mauser and Ludwig 2002), Rhine
(Nieuwkamer), Guadiana (Sorisi 2006) and Tagus (Andreu et al. 1996). In addition, DSS
have been built for different basins, for instance in Spain for the rivers Segura (Andreu et
al. 1996), Manzanares (Paredes et al. 2010); in Ireland for the Moy basin (Hall and
Murphy 2010), in Peru for the Rio Santa (Pukey and Escobar 2009, Read and McKinney
2010); in the U.S. for the upper Chattahoochee river (Johnson 1994), Trinity, San
18
Joaquin, San Francisco Bay and Delta (Cain et al. 1998), Sacramento (Purkey et al. 2008,
Yates et al. 2009), Sierra Nevada (Mehta et al. 2008, Viers et al. 2009); in Mexico for Rio
Conchos (Wagner and Vaquero 2002, Gomez et al. 2005, Amato et al. 2006, Gastelum et
al. 2009), Rio San Juan (Sandoval-Solis 2005), Rio Lerma (Vargas et al. 2004), Rio
Verde (Sandoval-Solis 2009.a), Rio Copalita (Sandoval-Solis 2009.b), just to mention a
few.
2.2 RIO GRANDE/RIO BRAVO BASIN
2.2.1 Introduction
The Rio Grande/Rio Bravo basin is a transboundary basin between the United
States (U.S.) and Mexico (Figure 2-3). It is a fundamental resource for the economy,
environment, health and quality of life for people in both countries and along the border.
Cities, such as Albuquerque, Las Cruces, El Paso, Brownsville and McAllen in the U.S.,
and Monterrey, Ciudad Juarez, Saltillo, Chihuahua, Matamoros and Reynosa in Mexico
depend on the water resources of this basin. The important agriculture economies of the
El Paso/Juarez valley, the lower Rio Grande valley and the Rio Conchos irrigation
districts also depend on the waters of this basin. The environmental health of the Big
Bend National and State Park in the U.S. and the protected areas of Cañón de Santa
Elena, Maderas del Carmen and Ocampo in Mexico are affected by the quantity, quality
and timing of the Rio Grande/Rio Bravo streamflows. In addition, international
obligations under the United States – Mexico Convention of 1906 and the Treaty of 1944
apply for both countries (IBWC 1906 and 1944). In this research, attention is focused on
the middle and lower part of the basin, from Elephant Butte dam in New Mexico to the
mouth of the Rio Grande/Rio Bravo at the Gulf of Mexico.
19
Figure 2-3: Rio Grande/Rio Bravo Basin
20
2.2.2 Background
Before the discovery of America, there is evidence that indigenous people used
the waters of the Rio Grande/Rio Bravo. In 1584 Spanish settlers found indigenous
inhabitants in the confluence of the Chama River and the Rio Grande/Rio Bravo, in what
is now Espanola city, New Mexico (Mills and Follett 1898). In Franklin/Paso del Norte
valley (which later become El Paso and Ciudad Juarez after 1889) there is evidence that
in 1600’s, indigenous inhabitants used to build a temporal weir (made form tree branches,
rocks and mud) to divert the water from the mainstream to their orchards (EnriquezCoyro 1976). In 1805, Alexander Humboldt (1966) described the crops grown in this
region (corn, wheat, grapes) and the construction of the temporal weir. Similarly,
indigenous inhabitants used the Rio Grande/Rio Bravo waters for agriculture purposes in
Presidio del Norte (Presidio, TX), Presidio de Rio Grande (Rio Grande City, TX), Laredo
and Refugio (Brownsville TX.) (Enriquez-Coyro 1976).
In 1836 the Rio Grande/Rio Bravo became a transboundary basin after Texas’
independence in the San Jacinto Battle (William 2004). After that, there were border
disputes between both parties, Texas and Mexico claimed the border at Rio Grande/Rio
Bravo del Norte and Nueces rivers, respectively. After two failed attempts, in 1845 the
Republic of Texas annexed to the United States of America (Fehrenbach 2000). The
border issues will become important after Texas’s annexation, which ultimately led into
the Mexican war (1946-1948). The Guadalupe-Hidalgo treaty settled this dispute between
both countries and defined the Rio Grande/Rio Bravo del Norte as the border (IBWC
1848). Later, in 1854 the Mesilla treaty (Gadsden Purchase) was the agreement that
defined the border between both countries as it is now. In the Guadalupe-Hidalgo treaty
was specified a navigability clause (Article VII) for the Rio Grande/Rio Bravo, this
21
clause drove some of the proposals and infrastructure designs of the river until the
signature of the treaty of 1944 (IBWC 1944) when this clause was nullified.
Since the signature of the Guadalupe-Hidalgo treaty in 1848 until 1877, water
related problems were minor in the Rio Grande/Rio Bravo basin (Enriquez-Coyro 1976).
In 1878, when Coronel Hatch was prosecuting bandits in the El Paso region, he noticed
problems of water allocation during drought periods in this region (Hatch 1878). The
same year, U.S. president Rutherford B. Hayes signed the Desert Land Act promoting the
economic development of arid regions in western U.S.; offering land to people for a very
small price with the only condition to irrigate the land bought for at least 3 years (Ganoe
1937). This act promoted a disproportioned expansion of agriculture land and water
consumption in Colorado and New Mexico from 1878 to 1896, leading to water scarcity
problems in the El Paso/Ciudad Juarez region. The previous situation was aggravated
with an eight year drought (1877 - 1884). In 1880 is dated the first international complain
regarding water allocation in El Paso/Ciudad Juarez region (Enriquez-Coyro 1976).
Because frequent problems of water allocation, constant channel changing (and
thus changing of the boundary), and the poor delineation of the boundaries in land, in
1889 it was established two International Boundary Commissions (IBC), one commission
who decides about water course changes and hydrologic problems, and another one for
boundary delineation. The IBC was extended indefinitely in 1900 and is the considered
the predecessor of the International Boundary and Water Commission (IBWC) who was
established later, in 1944 (IBWC 2010).
Approximately since 1900’s, the states of Colorado (1882), New Mexico (1898)
(Corbridge and Wilkinson 1985) and Texas (1913) (Hutchins et al. 2004) used the prior
appropriation system to assign water: “first in time, first in right”. In Texas, after the
1950’s drought the allocation system changed to a riparian system only for the Rio
22
Grande/Rio Bravo basin; in order to prioritize domestic, municipal and industrial use
above irrigation and mining (Yoskowitz 1999). In Mexico, riparian system applied since
the Spanish colonization (Enriquez-Coyro 1976), allocating water based on the type of
use, domestic and municipal use have higher priority than agriculture or industrial water
use. Before the Convention of 1906 there was no formal water management in the basin;
water was allocated locally, based on the availability of water and agreements between
water users (Corbridge and Wilkinson 1985).
2.2.2.1 Convention of 1906
Because of the continuous scarcity of water resources in the Rio Grande/Rio
Bravo after 1887, and the increasing difficulty to achieve agreements in the El
Paso/Ciudad Juarez region, a set of negotiations took place to define the water allocation
between both countries in this region, ending with the signature of the Convention of
1906.
Since 1887, several negotiations and actions took place to define the method to
divide water between both countries. Among the proposals, two are remarkable because
of their historic importance and opposition: (1) Mills and Garfias (engineers of the IBC)
proposed the construction of an international dam at El Paso dividing the water one third
for the U.S., one third for Mexico and one third for the river, the share of the river was
considered because of the navigability clause in the Guadalupe-Hidalgo treaty; and (2)
Powel (USGS director) proposed supplying water to agriculture users in Colorado and
New Mexico in order to maximize the irrigated area, and that after these appropriation,
there would not be water left for senior water rights at El Paso region and thus; the
necessity to eliminate the agriculture in this area (Enriquez-Coyro 1976).
23
Similarly, two doctrines of international water law are also remarkable because of
their opposition: Harmon and Vallarta. In 1890, Mexico’s general attorney Ignacio
Vallarta proposed: (a) water must be divided in halves between both countries; (b)
navigability of the Rio Grande/Rio Bravo clause defined in the Guadalupe Hidalgo treaty
was violated because of the diversion of water in Colorado and New Mexico; (c)
Powell‘s project not only accept the U.S. appropriation system but also, simplifies the
problem to maximize the U.S. irrigated area; (d) Mexico has the right not only to stop the
U.S. diversions, but also to revoked the existing water rights; and (e) Mexico has the right
to claim for a compensation (Enriquez-Coyro 1976). On the contrary, in 1895 U.S.
general attorney Judson Harmon proposed the absolute sovereignty doctrine: “The fact
that there is not enough water in the Rio Grande for the use of agriculture does not give
to Mexico the right to subject the United States to burden of arresting its development
and denying to its habitants the use of a provision which nature has supplied, entirely
within its own territory. The recognition of such a right is entirely inconsistent with the
sovereignty of the United States over its national domain.” Lately, Harmon expressed
that the solution of the conflict will be the negotiation of a treaty with Mexico and not the
unilateral position he expressed initially (Samaniego-Lopez 2004).
During 1887 until 1904 two main projects were discussed: (1) the Elephant Butte
dam project in New Mexico property of the Rio Grande Dam & Irrigation Company and
(2) Mills’ dam proposition in El Paso/Ciudad Juarez. In 1902 was published the
Reclamation Act that funded irrigation projects for the arid lands of 17 states in the
American West. In 1904 the Reclamation Service took control of the situation in the El
Paso/Ciudad Juarez region and the following year the Reclamation Service and the US
Geological Survey defined the first draft of what later became the Convention of 1906.
The project consisted in the construction of Elephant Butte reservoir and the distribution
24
of water to irrigate 97,000 acres in New Mexico, 53,000 acres in Texas and 25,000 acres
in Mexico. The water was distributed as follows: 55% to New Mexico (233,000 acrefeet- 287 million m3/year), 30% to Texas (127,000 acre-feet- 157 million m3/year) and
15% to Mexico (60,000 acre-feet - 74 million m3/year). The Convention of 1906
established the water management rules in the Rio Grande/Rio Bravo from Elephant
Butte dam in New Mexico to Fort Quitman, Texas.
2.2.2.2 Treaty of 1944
The Convention of 1906 only alleviated the problems along the Rio Grande/Rio
Bravo between El Paso/Ciudad Juarez to Fort Quitman, Texas. Conflicts between the
United States and Mexico were recurrent about water distribution in the Rio Colorado
and Rio Grande/Rio Bravo.
In the Rio Colorado, in the early 1900’s up to 1922, water conflicts involved the
distribution of water within seven states and Mexico, water distribution for the Imperial
irrigation district and frequent floods in the mouth of the river at the Golf of California
(Enriquez-Coyro 1976). In 1922 the seven states signed the Colorado River Compact
allocating the water between the upper (Wyoming, Colorado, Utah and New Mexico) and
lower (California, Arizona and Nevada) basin states (DOI 1922). While the Colorado
River Compact established the overall rules of water allocation within the U.S., the water
conflicts with Mexico were still unsolved.
Meanwhile in the Rio Grande/Rio Bravo, the agriculture in the basin prospered.
The lower Rio Grande valley, (McAllen-Brownsville/Reynosa-Matamoros area) grew in
the agriculture land from 5,000 hectare in 1908 to 154,000 hectare in 1935. At this
location it was estimated that two thirds of the water came from Mexican sources. In
addition, the variability of the water resources made impossible the full utilization of the
25
river, sudden floods were followed by extended periods of drought. The necessity to
control and regularize the river was evident if further development in the agriculture
sector was expected (Enriquez-Coyro 1976).
Non water factors delayed the negotiation of an international agreement that
would solved the water conflicts between both countries. The Mexican Revolution (19101921) and the First World War delayed the negotiations for a decade. In the 1920’s and
early 1930’s, several meetings and informal negotiations took place about water
distribution of the Colorado, Tijuana and the Rio Grande/Rio Bravo waters. During this
period the conflicts moved around the negotiation of all basins at the same time and the
amount of water compromised to deliver for both countries. The relationship between
both countries was very distant and tense from 1936 to 1939, Mexico started commercial
exchange with the axis powers and in 1937 the Mexican government nationalized the oil
industry from U.S. companies. Conciliation meetings happened in 1939 to negotiate the
compensation terms for U.S. companies due to the oil industry nationalization. The same
year the Second World War started, the United States entered the conflict in 1941 after
the Japanese bombing of Pearl Harbor, and Mexico declared the war on the axis powers
in 1942.
The negotiations for 1944 Treaty started in 1940. A full hydrologic study of the
Colorado and the Rio Grande/Rio Bravo was done to examine the best agreements for
both countries. Meanwhile in the Colorado the negotiations moved around the amount of
water delivered from the U.S. to Mexico; in the Rio Grande/Rio Bravo the situations was
the opposite, the negotiations focused on the amount of water delivered from Mexico to
the U.S. This unique condition where in one basin (Colorado) one country was the upper
riparian and in the other basin (Rio Grande/Rio Bravo) the same country was the lower
riparian, made possible a fair discussion of the treaty terms. It was impossible to be
26
negligent in one basin knowing that in the other basin the situation could be reverted. It is
also notable the competitive but friendly spirit of the negotiations and the political
willingness of Franklin D. Roosevelt and Manuel Avila Camacho administrations to
show that during war times it was possible to establish agreement between nations
(Enriquez-Coyro 1976). Finally, on February 3rd, 1944 was signed in Washington D.C.
the treaty between Mexico and the United States that defines the rules for water
allocation between both countries of the Colorado and Tijuana Rivers and of the Rio
Grande (IBWC 1944).With the signature of the treaty the International Boundary and
Water Commission (IBWC) was created, formed by two sections: the American and
Mexican section. The IBWC replace the International Boundary Commission (IBC).
2.2.2.3 After Treaties era
In this section is analyzed the period after the signature of the 1944 Treaty;
however, there is no “after treaties era” since the 1944 Treaty is a dynamic international
agreement that is amended each time a minute is signed. Up to now, there are 318
minutes and the last minute was signed on December 2010. Besides, there are two more
international agreements signed by the United States and Mexico after 1944, the
Chamizal Convention of 1963 (IBWC 1963) and the Treaty of 1970 (IBWC 1970). These
two treaties are more focused in the border line delineation and solution of conflicts
because of the changing in the Rio Grande/Rio Bravo course.
For the Rio Grande/Rio Bravo, the 1944 Treaty established the delivery of water
from Mexico to the United States of 1/3 of the flow reaching the Rio Grande/Rio Bravo
from 6 Mexican tributaries (Conchos, Arroyo Las Vacas, San Diego, San Rodrigo,
Escondido and Salado) provided that this third shall not be less, as an average amount in
cycles of 5 consecutive years, than 431.721106 m3/year, although such one third may
27
exceed this amount. Two international dams, Amistad and Falcon, were built to store
water for both countries. Also, it was provided that the treaty cycles can expire earlier
than five years, if the conservation capacity assigned to the U.S. in both international
dams is filled with water belonging to the U.S.
The technical report presented by Orive-Alba (1945) to the Mexican Chamber of
Senators shows the calculations used to define the U.S. and Mexican allotment in the
Treaty, and the expected deliveries of water from Mexico to the U.S. Two different cases
were considered by Orive-Alba to evaluate the treaty obligations. Case I only considers 5
years cycles, before the dam’s construction, when the system is considered to not be fully
developed. Historically, this case happened during the first 3 treaty cycles, from Oct/1953
to Sep/1958. Case II considers the system fully developed, after the international dams’
construction. In this case, during wet years the treaty cycles can expire earlier if the
conservation capacity assigned to the U.S. is filled. Historically, Case II happened since
treaty cycle 4 up to the present (treaty cycle 31).
Three performance criteria are used to analyze the performance expected when
the treaty was signed and what actually happened for the treaty deliveries from Mexico to
the U.S.: Reliability, Resilience and Vulnerability. Reliability refers to the frequency in
time an event is successful in relation to the total period of time analyzed. A successful
event is defined as the event when there is no deficit in the delivery of treaty obligations.
Resilience is the probability that once the system is in a deficit, the next period the
system recover to a successful event. Vulnerability is the expected value of the deficits, in
other words, it is the average of the deficits experienced. These performance criteria are
discussed in detail in Chapter 3: Performance Criteria.
28
Table 2-1: Reliability, Resilience and Vulnerability of the Mexican delivery of water
according to the 1944 Treaty.
Performance Criteria
Reliability
Resilience
Vulnerability
Chase I: System
Undeveloped
Expected Historical
(%)
(%)
56%
65%
10%
67%
100%
27%
Chase II: System
Developed
Expected Historical
(%)
(%)
42%
80%
9%
63%
67%
30%
For Case I (see Table 2-1), the reliability improved from an expected value of
56% to 67% that actually happened. This means that the system was in fewer times in
deficit than what was expected, 11% of the time less. Also, the system recovered faster,
the resilience increased from an expected value of 65% to an historic value of 100%.
Historically, when the system failed the following cycle the deficit was paid off. On the
contrary, the vulnerability got worse, from an expected value of 10% to an historic value
of 27%. When a deficit in the treaty obligation happened, it was of 27% of the treaty
obligations (2,159 million m3/cycle) instead of 10%, as it was planned. The people
involved in the treaty negotiations knew that the system will fail very frequently, in fact
44% of the time (1-Reliability) and that system does not recovered vary fast (65% of the
times around two out of three times), but they relied that the failures will be small (10%
of the treaty obligations) (Orive-Alba 1945). Historic data showed that the system does
not fail as much as they thought, only 33% of the time, and the recovery is faster (100%
of the times for Case I, from Oct/1953 to Sep/1968) but the deficits are much bigger of
what they planned (about 3 times bigger, 27% of the treaty obligations).
For Case II (see Table 2-1), as the system is right now, the reliability improved
from an expected value of 42% to an historic value of 63%. Historically, the system was
29
less time in a deficit of what was expected. However, the system recovered slower and
the deficits were bigger of what was expected. The quickness of recovery (Resilience)
decreased from an expected value of 80% to an historic value of 67%; historically it was
more difficult to recover from a deficit of what was expected. The severity of the deficits
(Vulnerability) increased from an expected value of 9% to an historic value of 30%.
When a deficit in the treaty obligation happened, it was of 30% of the treaty obligations
(30% of 2,159 million m3/cycle) instead of 9%, as it was planned. The people involved in
the treaty negotiations knew that the system will fail very frequently, in fact 58% of the
time! (Orive-Alba 1945, Enriquez-Coyro 1976). However, they relied that the failures
will be small (9% of the treaty obligations), and the system will recover from deficit very
frequently (80% of the times; around four out of five times). Historic data showed that
the system does not fail as much as they thought, only 47% of the time (1-Reliability),
but the recovery is slower (67% of the times, two out of thee) and the deficits are much
bigger of what they planned (more than 3 times bigger, 30% of the treaty obligations). In
conclusion, historical treaty deliveries have shown different performance than the 1944
Treaty signature premises: higher reliability, lower resilience and high vulnerability.
2.2.3 Challenges
2.2.3.1 Planning and management
Over allocation of water rights
In 2007 the Rio Grande/Rio Bravo was named one of the world’s top ten
endangered rivers by the World Wildlife Fund (WWF 2007) because of the mismatch
between the water availability and water rights conferred in the basin. In Mexico, the
over allocation of water rights was identified since late 1990’s, when the federal
government made a census to identify all the water users in the basin (SEMARNAT
30
1995, SEMARNAT 2002). Later, the minister of agriculture made public the PADUA
program, with the objective to reduce the water rights conferred to irrigation districts in
order to match the demand with the availability of water. This program is available for
eleven irrigation districts from which six are located in the Rio Grande/Rio Bravo basin
(SAGARPA 2003). Furthermore, in 2008 CONAGUA (water authority in Mexico)
published the annual water availability study for the Rio Grande/ Rio Bravo (CONAGUA
2008.b). This study concluded there are more water rights than the actual natural
availability of this resource.
In the United States, during the last drought (1994-2003) the water supply for the
United States was compromised. At the beginning of the drought (1994-1996) the water
supply for agriculture water users below Falcon was on average 78% (1400 million
m3/year) of their full allocation demand (1801 million m3/year), for the rest of the
drought (1997-2004) the water supply was on average 53% (950 million m3/year) of the
full allocation demand (IBWC 2009). This uncertainty in the water supply provoked the
75th Texas Legislature to order a study (Brandes 2004) that defined water availability,
water use limits and vulnerabilities of the system (TWDB 2001). As a result, the “Current
Allocation” for US water users other than municipal, domestic and industrial was set at
70% of the full allocation demand, acknowledging the over allocation of water rights
(TCEQ 2007). The current allocation has been further reduced to 62% of the full
allocation demand (personal communication, Carlos Rubenstein, Commissioner, TCEQ,
October 2009).
31
Figure 2-4 a and c show the water consumption for Mexican water users along the
Rio Grande/Rio Bravo mainstream and in the tributaries, respectively (CONAGUA
2008.b, Sandoval-Solis 2011). Both figures show a linear increase in the water
consumption due to irrigation district expansion, mostly from 1965 to 1994, and after
that, a dramatic decrease in their water supply during the 90’s drought (1994-2007).
Water consumption before the 90’s drought was much higher than the annual average
consumption (1950 to 2004) of water users along the Rio Grande/Rio Bravo and in
Mexican tributaries, which are 1,576 and 2,392 million m3, respectively.
Figure 2-4 b shows the water consumption for U.S. water users along the Rio
Grande/Rio Bravo mainstream (IBWC 2009, Sandoval-Solis 2011). Water consumption
for U.S. water users has been close to the mean annual value (1,442 million m3) except
for 1989 when more than 2,000 million m3 were consumed. Notice that the mean annual
water consumption for Mexican and U.S. water users along the Rio Grande/Rio Bravo
mainstream is about the same, 1,576 and 1,442 million m3 respectively. The main
difference is that U.S. water consumption does not vary as much as in Mexico.
In the early 2000’s, reduction in the irrigation districts’ water rights was discussed
by authorities from both countries (SAGARPA 2003, IBWC 2003, Brandes 2004); the
drought of the 90’s showed that the prior 1994 water consumption was unsustainable.
U.S. and Mexican authorities recognized that it was physically impossible to continue
providing the water consumption of the early 90’s (1990-1994). In 2004, water rights in
Mexico and the US were estimated to be 4,532 and 2,129 million m3/year, respectively
(CONAGUA 2004, Brandes 2004). Recently, several policies have been implemented to
reduce the water rights in the basin, such as buy-back of water rights (Chapter 6.2.1),
infrastructure improvements (Chapter 6.2.3) and water rights reduction (Chapter 6.3.1).
In 2008, water rights in Mexico and the US have been reduced to 4,401 and 1,953 million
32
m3/year, respectively. These values are still above the historic mean annual water
consumption for Mexico and the U.S., which are 3,968 and 1,442 million m3,
respectively (Sandoval-Solis 2011). Furthermore, the previous analysis does not consider
water for the environment; these values shows the problem of over-allocation of water
rights in the basin.
Water Consumption (million m3)
2,500
3,000
Annual
Mean
2,000
1,500
1,000
500
0
2,500
1,500
1,000
500
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
0
b) U.S. Rio Grande/Bravo
Annual
Mean
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Water Consumption (million m3)
a) Mexico Rio Grande/Bravo
4,500
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
0
Annual
Mean
2,000
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Water Consumption (million m3)
3,000
c) Mexico All Tributaries
Figure 2-4: Water consumption in Mexico and the U.S. along the Rio Grande/Rio Bravo
and in Mexican tributaries.
33
Low efficiency in the system
In the basin, agriculture accounts for 84% of the total water demand; water in the
basin is mainly used for irrigation. In Mexico, conveyance and applications efficiencies
for agriculture are usually low (Collado 2002); for instance, prior 2003 the global
efficiency in irrigation district 005 Delicias was estimated of 33%, meaning that only
33% of the water diverted from the reservoir will actually be consumed by the crop
(IBWC 2003). That year was implemented an agreement through Minute 309 to improve
the infrastructure in irrigation districts 005 Delicias, 090 Bajo Rio Conchos and 103 Rio
Florido to increase their global efficiency from 33%, 35% and 33% to 55%, 47% and
48%, respectively (IBWC 2003). The prior improvement efficiencies (<35%) can give us
an idea what are the efficiencies in other irrigation districts without infrastructure
improvements. Unfortunately, improvement infrastructure programs, such as Minute 309,
have not been implemented in other irrigation districts.
In the lower Rio Grande valley and Maverick county, prior to 2000 conveyance
efficiencies by irrigations Districts range from 40% to 95% (Fipps 2000), with an average
conveyance efficiency of 71%. On farm efficiencies vary from 30% to 80%; these values
are uncertain given the lack of data and collaboration from irrigation districts in this area
(Fipps and Pope 2004). Considering the previous uncertainty, global efficiency can vary
from 21% to 76%. From 2002 to 2004, several water conservation projects were
implemented in the lower Rio Grande Valley (Hidalgo and Cameron counties), and
Maverick county to improve the conveyance efficiencies in irrigation districts (NADB
2010.a and 2010.b); although, water savings from these project has not been published.
34
Undefined Water Regulation
Historically, water supply in the basin has varied significantly, showing
inconsistency in water management of the basin. For Mexico, Figure 2-5 shows the
historic water consumption from 1950 to 2004 along the Rio Grande/Rio Bravo and in
the Mexican tributaries (CONAGUA 2008.b). This figures show how variable has been
the water supply for Mexican water users; while municipal and domestic users have
secured their water supply, irrigation districts have experienced uncertainty in their water
allocation. In 2002 there was an unsuccessful initiative to implement a regulation in the
basin (Collado 2002); up to now, there is no specific regulation to allocate water for
irrigation districts that accounts for 84% of the water rights. Similarly, there is no policy
Water Concumption (million m3)
3,000
Annual
Mean
2,500
2,000
1,500
1,000
500
Water Consumption (million m3)
to deliver treaty obligations from Mexico to the U.S. according to the 1944 treaty.
Annual
Mean
4,500
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
0
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
0
a) Along the Rio Grande/Rio Bravo
b) All Tributaries
Figure 2-5: Water Consumption for Mexico 1950-2004
35
In the U.S, regulations are already defined to allocate water in the Rio Grande/Rio
Bravo basin (TCEQ 1938 and 2006); however, water supply has varied along the time
(see Figure 2-6) (IBWC 2009). During the 1944 treaty signature, the consumptive use of
water along the Rio Grande/Rio Bravo mainstream was estimated 1,949 million m3/year
(Sandoval-Solis and McKinney 2011). During the drought of the 50’s (1948-1957), water
supply was reduced to 1,190 million m3 on average per year, 66% of their full allocation
water right (1,802 million m3/year). In the following three decades (60’s to 80’s), water
supply used to be around the mean, 1442 million m3/year, 80% of the full allocation right.
Because of the drought of the 90’s (1994-2007), water supply for agriculture and mining
water use in the thirteen Water Master Sections have been reduced progressively; for
instance, in 2004 water rights were reduced to 70% of their full allocation (Brandes 2004)
and recently, in 2009, this value has been reduced to 62% (personal communication,
Carlos Rubenstein, Commissioner, TCEQ, October 2009).
Water Consumption (million m3)
3,000
Annual
Mean
2,500
2,000
1,500
1,000
500
2000
1995
1990
1985
1980
1975
1970
1965
1960
1955
1950
0
Figure 2-6: Water Consumption for the U.S., 1950-2004
36
2.2.3.2 Water Quality
Besides water quantity, there are issues regarding water quality in the Rio
Grande/Rio Bravo basin. To assess this problem, the TCEQ has divided the basin in three
regions: upper basin, from El Paso/Cd. Juarez to Amistad Reservoir; middle basin, from
Amistad to Falcon; and the lower basin, from Falcon to the Gulf of Mexico. Primary
water quality concerns include: a) high bacteria levels in all regions, it is suspected that
communities are discharging their wastewater into the mainstream without any treatment;
b) high salinity levels (chloride, sulfate and TDS) in the upper region, this can be caused
due to returns of irrigation districts, invasive species, scarcity of water, among others
problems; c) high nutrients level (ammonia and phosphorus) in all regions, because of
municipal discharged without any treatment; and d) excessive growth of aquatic weeds in
the lower basin (IBWC 2008, Ingol-Blanco and McKinney 2009). Besides, toxicity
studies along the border have found high levels of toxics in water (PCB’s, Cyanide,
mercury and residual chlorine), sediment and fish (TCEQ 1995). Despite all of this, the
situation has improved in recent years because of the investment in wastewater and water
systems (Texas Environmental Profiles 2004, NADB 2010.a and 2010.b); bi-national
cooperation, such as the Border 2012 project have provided guidance and financial
resources to attend public health and water quality problems along the border (EPASEMARNAT 2009), but water quality is still an issue to improve in the basin (IBWC
2008).
2.2.3.3 Environment
In addition to the problems of water quantity and quality, environmental problems
are also present in the Rio Grande/Rio Bravo Basin. Prior the dam’s construction, the Rio
Grande/Rio Bravo was constituted by two hydrological regimes: (1) in the northern
branch, above Ojinaga/Presidio, the flood regime was snowmelt driven from the Rocky
37
Mountains, with a peak flow in late spring, meanwhile (2) in the southern branch, below
Ojinaga/Presidio, the flood regime was driven by summer-autumn rainfall, mostly water
coming from the Rio Conchos whose headwaters are in the Sierra Madre Occidental
(Schmidt et al. 2003). Even though the drainage area of the northern branch is bigger than
the Rio Conchos sub-basin, the flow provided by the Rio Conchos was much larger than
the northern branch flow. The alteration of the natural regime has threatened the
environmental health of aquatic and riparian ecosystems.
Reservoir alteration
Reservoir construction in the basin degraded the environmental conditions in the
basin. Figure 2-7 and Figure 2-8 shows the reservoir construction for the United States
and Mexico, respectively. There is evidence that in the Big Bend reach before the mid
1940’s, the Rio Grande/Rio Bravo mainstream preserved a wide, sandy and multithreaded river. However, after the mid 1940’s, a progressive channel narrowing has been
the constant in this reach, temporally interrupted by occasional large floods that widen
the channel and channel narrowing resumed again (Dean and Schmidt 2011). Narrowing
has occurred by the vertical accretion of fine-grained deposit on top of sand and gravel
bars. Sand and gravel bars that used to be part of the dynamic channel were progressively
invaded by vegetation. The invasion of non native species, such as salt cedar (Tamarisk
spp.) since 1910’s or giant cane (Arundo donax) since 1938 (Everitt 1998), has
exacerbated the process of channel narrowing and vertical accretion. The geomorphic
nature of the Rio Grande/Rio Bravo has changed from a wide, laterally unstable, multithread river before mid 1940s; to a stable, single-thread channel with cohesive, vertical
blanks, and few active in channel bars after 1940 (Dean and Schmidt 2011). This shift in
the geomorphic conditions was caused primarily by dams’ construction, mostly since
1915, and it has been exacerbated by the invasion of non-native species after late 1930’s.
38
39
Figure 2-8: Reservoir development in Mexico for the Rio Grande/Rio Bravo
2010
2000
1990
1980
1970
6,000
El Cuchillo
San Gabriel
C. Prieto
Luis L. Leon
Amistad
2010
2000
1990
1980
1970
1960
1950
1940
El Vado
Red Bluff
Caballo
Falcon
Cochiti
Heron
Abiquiu
16,000
1960
8,000
1930
14,000
1950
16,000
Marte R. Gomez
Francisco I. Madero
Falcon
18,000
1940
12,000
1920
12,000
1930
14,000
Venustiano Carranza
4,000
Elephant Butte
6,000
1910
8,000
1920
10,000
La Boquilla
1900
Total Storage (million m3)
10,000
1910
1900
Storage (million m3)
18,000
Total Storage
Active Storage
2,000
-
Figure 2-7: Reservoir development in the United States for the Rio Grande/Rio Bravo
Total Storage
Active Storage
4,000
2,000
-
Another point of environmental concern is the outlet of the river at the Gulf of
Mexico. In February of 2001 the river mouth was blocked by a sand bar caused by low
flow conditions due to the 90’s drought, upstream diversion and invasive aquatic
vegetation (Mathis et al. 2006, Blankinship 2005); it remained closed until September
2001 when the IBWC dredged it open (IBWC 2002). Subsequent tidal water changes
again closed the mouth until November 2002, when higher tides and increased rainfall
runoff partially opened it. The scarcity of flow in this reach is a threat to the estuary’s
sustainability; side effects include degradation of the environment, lost of species and
saline intrusion in aquifers, among others.
Ecosystems
The Rio Grande/Rio Bravo Basin is one of the most biologically-diverse regions
in North America, possessing a range of important aquatic and terrestrial ecosystems
(WWF 2007). It traverses three major ecological regions (Southern Rocky Mountains;
Chihuahua Desert; Tamaulipas Thorn Scrub) exhibiting a mosaic of mountain, desert and
coastal habitats. The lower Rio Bravo valley provides habitat for millions of migratory
birds to feed and rest during migration, it is a major bird watching site in North America
(WBC 2011). Reptiles and amphibians thrive in wetlands through the basin, including
many sea turtles, lizards, snakes, frogs and salamanders.
Degradation of river water quality and riparian vegetation has changed
significantly over time. Some of the threatened or endangered species include: the bald
eagle (Haliaeetus leucocephalus), Gulf Coast jaguarundi (Herpailurus
yagouaroundi
cacomitli), star cactus (Astrophytum asterias), Mexican long-nosed bat (Leptonycteris
nivalis), Rio Grande silvery minnow (Hybognathus amarus), Walker’s manioc (Manihot
walkerae), and black-footed ferret (Mustela nigripes) (USC 1973). Causative factors
include construction of dams, variable water flow rates, urbanization, ecosystem
40
fragmentation, and introduction of non-native species. Hydrologic modifications and
exotic species have worsened the conditions for native species. Few undisturbed, natural
communities remain in the lower portion of the basin. The final 48 km of the Rio Bravo
is a tidal river system, with the offshore portion of the Gulf of Mexico directly influenced
by the river’s freshwater discharge plume comprising the Rio Grande/Rio Bravo estuary
system.
Undefined Environmental Water Rights
Despite the fact that regulations on both countries considered the environmental
protection of ecosystems (USC 1973 and CONAGUA 2008.a), there is no water
management policy in place that delivers water for environmental purposes. Historically,
this basin has been manipulated in an exclusive human water resource management
(Enriquez-Coyro, 1976), not considering the environmental needs for the native
ecosystems. The Convention of 1906 (IBWC 1906), the Rio Grande Compact (TCEQ
1939) and the Treaty of 1944 (IBWC 1944) prove the fact that the water in this basin was
thought to be used exclusively for human benefit. The water allocation in these
agreements obeys exclusively the human concerns, leaving out the natural water
requirements of the basin. In fact, article 3 of the treaty of 1944 does not mention the
“Environment” as beneficial use of water (IBWC 1944).
In addition, there is a lack of environmental flow estimation along the basin;
while some regulations provide the legal framework to protect the environment
(CONAGUA 2008.a, LST 2007); these regulations cannot be enforced due to the absence
of environmental flows estimation along the rivers. In recent years, there has been
certain progress regarding this topic; in 2006 the World Wildlife Fund estimated the
environmental flows in 9 locations along the Rio Conchos basin through the use of the
Building Block Method (WWF 2006). The geomorphology, flora and fauna (fish and
41
invertebrates) were considered to determine the maintenance and drought flows necessary
to meet the environmental requirements. Besides, a first draft of environmental flows
have been determined for the Big Bend reach, along the Rio Grande/Rio Bravo
mainstream, this estimation was obtained through a historic hydrologic analysis
(Sandoval-Solis et al. 2010).
Invasive species
In addition to the previous problems, at least three invasive species are
proliferating in the Rio Grande/Rio Bravo basin: 1) Russian Olive (Eleagnus
angustifolia) in the upper basin, above Elephant Butte reservoir, 2) salt cedar or Tamarisk
(Tamarix spp) and 3) giant cane (Arundo donax), both of them in the middle basin, from
El Paso/Ciudad Juarez Valley to Amistad reservoir (Everitt 1998, Dudley et al. 2000,
Schmidt et al. 2003). Salt cedar is a highly drought resilient species that consumes
important amounts of water and increases the salinity of soil, it is a paramount
opportunistic species that spreads and reproduce very efficiently occupying the space and
resources of native species.
There have been several efforts to eradicate invasive species from the basin, the
Big Bend National Park Service have physically removed plants, use herbicides,
introduced tamarisk beetles (Diorhabda carinulata) and evaluated the eradication of nonative species by floods. Preliminary results of eradication efforts have shown that
flooding mitigates the impact of Tamarisk on soil salt loading (Cederborg et al. 2008). In
2008, most of the tamarisk located along the river in the Big Bend reach was removed by
the floods of that year. This pest control policy is very unlikely, the construction of large
reservoirs in the basin has decreased the occurrence of these events, collaborating in the
proliferation of tamarisk. Besides this is an undesired policy by people living close the
river.
42
2.2.4 Current Status
Regarding the water management in the basin, after the publication of the water
availability for Mexican water users by CONAGUA (2008.b), the Rio Bravo basin
council has started a process of negotiation were it will be defined the regulation to
allocate water for municipalities and irrigation districts in the basin (Arreguin 2010),
these water rights account for 99% of the total Mexican water rights. In order to build
trust among the parties, the basin council is building a water planning model where
policies will be tested. This planning model will be built using the algorithms and
allocation policies of the Rio Grande/Rio Bravo WEAP model built in the present
research; besides several policies proposed in the present research will be considered by
the Mexican basin council. In 2010, regional water plans for regions E, J, and M have
been published by the TWDB (2010.a, b and c). These documents describe several water
management policies that will be implemented to deal with the increase of population and
energy requirement, such as:
water conservation measures in municipalities and
irrigation, reuse of water either from municipal or agriculture drains, groundwater
development, brackish and seawater desalination, acquisition of additional water rights.
Out of the previous policies, four policies account for 75% of the water savings planned:
1) increase in efficiency of on-farm water application, 2) water conservation in
conveyance for irrigation, 3) acquisition of water rights through purchase and 4) brackish
desalination.
Regarding treaty obligations, cycle 31 is the current treaty cycle, it started on
October 26th 2010. Cycle 30 was closed on October 25th 2010, it lasted about one year
and a half, and it was closed because of the filling of the US storage capacity at both
international reservoirs. Up to February 2011, the storage for the US and Mexico at the
international reservoirs are 97% and 90% of their conservation capacity respectively;
43
2008, 2009 and 2010 have been wet years (IBWC 2011). Reservoirs in Mexico are above
90% of their conservation capacity; main reservoirs in Rio Conchos, Salado and San Juan
are above 94% of their conservation capacity (CILA 2011). In the US, Elephant Butte
and Caballo reservoirs are at their 24% and 11% conservation capacity, respectively
(IBWC 2011).
Regarding the environment, in 2006 the environmental flows for nine control
points in the Conchos basin were estimated by the World Wildlife Fund (Chapter 6.2.5);
these flows are used to evaluate the environmental requirements for the basin. More
recently, in 2010 the author proposed an annual hydrograph for environmental restoration
flows at the Big Bend Reach (Sandoval-Solis et al. 2010), this hydrograph is based on the
hydrologic characteristics prior 1946, when the Rio Grande/Rio Bravo maintained a
wide, sandy, multi-thread channel (Dean and Schmidt 2011). This investigation is
currently undergoing and not included in the present document; at this moment, the
author is investigating how to operate the infrastructure in order to obtain environmental
flows for this region without harming water users, the treaty obligations or increasing the
flooding risk at Presidio/Ojinaga. In Texas, Senate Bill 3 provides the legal framework to
determine and promote environmental flows for the state (LST 2007). In March 2011, the
Science Advisory Committee will be formed; they will provide an objective perspective,
evaluation and estimation of environmental flows in the Rio Grande/Rio Bravo stream to
the Advisory Group, which is integrated by members of the senate, House of
Representatives and people appointed by the Governor. In the lower Rio Grande valley,
the World Birding Center (WBC) was created as a network of sites for bird watching;
along their 9 locations it is possible to appreciate the ecological treasures of the lower Rio
Grande valley. The objective of the WBC is to protect native habitat and ecosystems
while increasing the understanding and appreciation of birds and wildlife (WBC 2011).
44
Regarding water quality, the IBWC Texas Clean River Program has conducted
several monitoring campaigns along the Rio Grande/Rio Bravo mainstream. The analysis
of these data has shown problems of bacteria, high salinity, nutrients, and excessive
growth of aquatic weeds in the lower Rio Grande basin (IBWC 2008). In 2010, two were
the main concerns downstream Falcon to the Gulf of Mexico: 1) bacteria, listed as the
main concern and 2) mercury, dissolved oxygen and nutrients. The proposed work plan
of the Clean River Program for 2010-2011 includes water quality data monitoring in 46
stations, data analysis and reporting, stakeholder participation and outreach. In March
2011, the IBWC is organizing a summit about water quality and sanitation along the
border. In this summit will be addressed the current problematic and possible solutions to
water quality, sanitation, financing along the US-Mexico border.
Regarding politics between Mexico and the U.S., during the drought of the 90’s
(1994-2007), relations between both countries were tense because of the increase in water
debt of Mexico. Presidents George W. Bush and Vicente Fox organized meetings to
discern solutions about the problematic of water scarcity, Mexico’s water debt and how it
will be paid; Minutes 307, 308 and 309 are the agreements of these presidential meetings
(IBWC 2001, 2002 and 2003). In the Colorado River, since 1988, lining the All
American Canal (AAC) started sounding as an option to save water for California; in
2002-2003 this project gained momentum and the final design for the AAC was
authorized by the California legislature in September 2003 (USBR 2006). Savings of the
lining of the ACC were estimated of 67,700 acre-foot/year (83.5 million m3/year). The
groundwater hydrology in this region conveyed the infiltration losses of the AAC to
Mexican territory, Mexican farmers and the Colorado Delta habitat were benefited from
these losses. Because of the Mexican water debt in the Rio Grande/Rio Bravo, Mexican
authorities in the Colorado delta did not raise any claim about the drawbacks that the
45
lining of the AAC would provoke to farmers and the environment (Personal
communication, Carlos A. de la Parra, El Colegio de la Frontera, 2010); they did not have
a strong argument for claiming harm considering that farmers in Texas were affected by
the unmet of Treaty obligations from Mexico. Once again, problems in one basin, the Rio
Grande/Rio Bravo, affected the management on the other basin, the Colorado River.
When the Mexican water debt was paid in 2007 (IBWC 2007), Mexico started claiming
affectations because of the lining of the ACC but it was too late, the project already
started in June 2007 (USBR 2010) and despite the fact of the NGOs suited the State of
California, in 2010 the lining of the canal was completed (USBR 2010).
In Mexico, politics have been related to downstream – upstream water users, the
state of Tamaulipas (downstream) against Chihuahua (upstream) state and federal versus
regional water management. In 1994 was founded the Rio Bravo Basin Council, an
organisms whose objective is to determine efficient policies to allocate water in the Rio
Bravo (CTMMA 2001). This public organism is in charge of the decision making process
for the water planning and management of the basin. The Basin Council is integrated by
representatives of: a) each basin’s state, b) water users and c) federal government
(CONAGUA 2008.a). The basin council is in charge of defining rules (regulations) for
water allocation in the basin, in Mexican territory. In 2008, the water availability study
was published as an agreement of the basin council (CONAGUA 2008.b); this is the first
step to define a regulation for water allocation in the basin. At this moment, the basin
council is calculating the naturalized flows for the Rio Grande/Rio Bravo basin in
Mexican territory. The politics of the basin (discussions, decisions, and agreements) are
expressed on this council; this is the place where upstream (Chihuahua) and downstream
(Tamaulipas) users defend their positions and negotiate about water allocation, rules and
46
action that will benefit their interest. Results of this research have been presented to the
basin council.
47
Chapter 3 Methodology
In this chapter is defined the methodology used to evaluate water management
policies in large scale basins. The first section presents the performance criteria used to
evaluate essential or desired characteristics required in the water management for water
users, the environment or system requirements. The second section explains the
summarization of performance criteria results by using the Sustainability Index and the
Relative Sustainability. This section explains the properties and improvements proposed
for the Sustainability Index as well as its calculation procedure. Also in this section is
introduced the Relative Sustainability, which is an index that summarizes the results of
Sustainability Indices. The Relative Sustainability is useful to show results for water
users’ groups. The third section describes the integration of results.
3.1 PERFORMANCE CRITERIA
Performance criteria are used to evaluate and compare the performance of water
management policies. They evaluate essential or desired characteristics required in the
water management for water users, the environment or system requirements; and make
possible their comparison with alternative policies.
Performance criteria using central measures of location have been used to
evaluate water resources systems. Examples of these performance criteria are, among
others, average: storage, water supply, evaporation, treaty delivery, municipal shortfalls
(deficits), and outflow of water from a system (Vigerstol 2002). Probability based
performance criteria include time-based (annual, monthly) and volumetric reliability
(TCEQ 2007), resilience (Hashimoto et al. 1982).
48
For each water user, environmental and system requirements, five performance
criteria are calculated:
1. Reliability –accounts for the period of time the water demand is fully supplied;
2. Resilience – accounts for the policy’s adaptability to hydrologic changing conditions;
3. Vulnerability – account for the expected severity of the deficits;
4. Maximum Deficit – account for the worst deficit case; and
5. Standard Deviation – accounts for the variability in the water supply.
3.1.1 Reliability
Reliability is the probability that a water demand is fully supplied during the
period of simulation (Klemes et al. 1981; Hashimoto et al. 1982). The time based
reliability (McMahon et al. 2006) is considered; which is the portion of time that water
demand is fully supplied. We define a deficit as (Loucks 1997):
,
,
,
0 ,
Equation3‐1
,
where: XiTarget,t is the water demand for the ith water user, and XiSupplied,t is the water
supplied in the tth time period. Finally, the reliability for the ith user is:
#
Equation3‐2
where n is number of time intervals considered, often used the total number of years or
months, depending on the water management unit of time.
49
3.1.2 Resilience
Resilience is the system’s capacity to adapt to changing conditions. Since climate
conditions are no longer steady, resilience must be considered as a statistic that assesses
the flexibility of water management policies to adapt to changing conditions (WHO 2009;
IPCC 2007.b). The classic definition of resilience is the probability that a system recovers
from a period of failure, e.g., a deficit in water supply (Matalas and Fiering 1977;
Hashimoto et al. 1982). Moy et al. (1986) used the maximum number of consecutives
deficit periods prior to recovery as an alternative definition of resilience. According to
Hashimoto et al. (1982), resilience is the probability that a year of no-deficit follows a
year of deficit in the water supply for the ith water user. This is a useful statistic to assess
the recovery of the system once it has failed. Resilience is expressed as:
#
#
Equation3‐3
3.1.3 Vulnerability
Vulnerability is the likely value of deficits, if they occur (Hashimoto et al. 1982).
Essentially, vulnerability expresses the severity of failures. Vulnerability can be
expressed as: (1) the average failure (Loucks and van Beek 2005); (2) the maximum of
the average shortfalls over all continuous failure periods (Hashimoto et al. 1982;
McMahon et al. 2006); and (3) the probability of exceedance over a certain deficit
threshold (Mendoza et al. 1997). The first approach is used, the expected value of
deficits. Dimensionless vulnerability is defined by dividing the average annual deficit by
the annual water demand for the ith water user:
∑
#
50
Equation3‐4
3.1.4 Maximum Deficit
The maximum deficit, if they occur, is the worst-case deficit for the ith water user
′
max
Equation3‐5
A dimensionless maximum deficit is used by dividing the volumetric maximum
deficit by the annual water demand for the ith water user
′
Equation3‐6
3.1.5 Standard Deviation
The variance of the water supply for the ith water user is:
′
,
∑
Equation3‐7
Where:
∑
,
Equation3‐8
Thus the standard deviation of the water supplied for the ith water user in period t
is:
′
Equation3‐9
′
This performance criterion indicates the variability of the water supply when part
or all of a user’s water demand is not supplied from controlled facilities, such as,
51
unregulated rivers. A dimensionless standard deviation can be defined by dividing the
volumetric standard deviation (7) by the water demand
′
Equation3‐10
As shown in Eq. 3-10, the standard deviation (
dividing it by the water demand (
′
) is scaled (standardized)
), therefore the standard deviation is expressed
as a percentage of the water demand. The purpose of this standardization is to obtain a
criterion that varies from zero to one; this is a requirement for any criterion that is
included in the Sustainability Index (explained in the following section). For the
particular case of the Rio Grande/Rio Bravo basin, the water demand (
) scales the
Standard Deviation criterion ( ), providing a range of values from zero to one. When
using any statistical criterion, such as: Vulnerability, Maximum Deficit, Standard
Deviation, or Volumetric Reliability (McMahon et al. 2006), it must be guaranteed that
the standardization value provides a criterion varying from zero to one.
3.2 SUSTAINABILITY INDEX
Indices represent aggregate measures of a combination of complex development
phenomena (Booysen 2002), or in other words, “synthesis of numerous factors into one
given factor” (Sainz 1989). Several indexes have been developed for environmental
processes such as the Environmental Index (Howmiller and Scott 1977; Milbrink 1983),
Environmental Sustainability Index (Esty et al. 2005), the Multi-attributed Environmental
Index (Hajkowicz 2005); and also some indices specifically for water resources, such as
the Drought Risk Index (Zongxue et al. 1998), the Palmer Drought Severity Index
(Palmer 1965), Fairness (Lence et al. 1977), Reversibility (Fanai and Burn 1997) and
Consensus (Simonovic 1998).
52
In order to quantify the sustainability of water resources systems, Loucks (1997)
proposed the Sustainability Index, with the objective to facilitate the evaluation and
comparison of water management policies. The Sustainability Index is a summary index
that measures the sustainability of water resources systems; it can be used to estimate the
sustainability for water users and to obtain the relative sustainability by comparing the
sustainability index among several water policies proposed. Frequently, indices are
criticized because they are seen as a combination of disparate items (Hopkins 1991). The
Sustainability Index summarizes essential performance parameters of water management
in a meaningful manner, rather than adding factors of broad, sometimes unrelated, and
distant categories.
3.2.1 By User
Loucks (1997) proposed the following sustainability index for the ith water user
∗
∗ 1
Equation3‐11
This sustainability index has the properties of: (1) its values varies from 0 to 1, or
as a percentage from 0 to 100%; (2) if one of the three performance criteria is zero, the
sustainability will be zero also; and (3) there is an implicit weighting, the index gives
added weight to the criteria having the worst performance. The multiplicative
computation of the sustainability index, rather than the additive form, considers each
criterion as essential and non-substitutable. Sagar and Najanm (1998) suggested this as
the proper manner for integrating performance criteria. The sustainability index is a
meaningful mathematical approach to estimating the sustainability for a water user.
53
A variation of Loucks’ sustainability index is proposed in this research, with the
index defined as a geometric mean of M performance criteria (Cim) for the ith water user
∏
C
Equation3‐12
For instance, if three performance criteria (M=3) are selected: Ci1 = Reli, Ci2 =
Resi, and Ci3 = 1-Vuli; the sustainability index for the ith water user is
∗
∗ 1
Equation3‐13
This sustainability index satisfies the properties of the sustainability index defined
by Loucks (1997), but, in addition, has the following improvements:
Content – Allows the inclusion of other criteria of interest according to the
necessities of each case. The sustainability index is not longer a fixed performance
criteria related to water quantity; performance criteria of water quality and environmental
performance might be included in the sustainability index. For instance, if the Total
Dissolved Solids (TDS) of the water delivered to a user must be below a permitted value,
the reliability for TDS not exceeding the desired threshold can be calculated and included
in the sustainability index. Notice that the criteria (Cim) included in Equation 3-12 must
have a scale from 0 to 1 and the desired criteria values tend to 1. Scaling and
complements 1-Cim can be applied prior to including any performance criteria into
Equation 3-12.
Clarity – the use of the geometric average scales the values of the sustainability
index, generating numbers that are more practical to interpret and communicate. Suppose
that a certain water user has a reliability, resilience and vulnerability of 50% for each
54
performance criteria. The sustainability index calculated with the prior definition
(Equation 3-11) and the proposed index (Equation 3-12) are 13% and 50%, respectively.
The latter is more like an arithmetic average which may be viewed as being more realistic
or intuitive than the former index that leads to a 13%, rather than a 50% value. The
scaling of the sustainability index does not obscure poor performance; its only purpose is
to scale the values and make the index more practical. Suppose the reliability for the
water user increases from 50% to 60%; the original and proposed sustainability index
values are 15% and 53%, respectively. Once again, the proposed index is easier to
explain and is more encouraging. In addition, more than 3 parameters can be included in
the sustainability index, the product of several factors will result in small numbers and
without scaling, changes in the sustainability index might be difficult to discern.
Flexibility – Several structures for the sustainability index might be applied in the
same basin for different water users or types of use. For instance, sustainability indices
for municipal or recreational water use may be integrated with different performance
criteria than an index for agriculture water use. Water quality and environmental
performance criteria may be included for municipal and recreational water use,
respectively, while the standard sustainability index (Equation 3-13) might be appropriate
for agriculture use. Sustainability does not mean the same thing for all water users and
the proposed index allows it to be adjusted to suit the user or use of water.
The improvements to the sustainability index are meaningful and not merely
mathematical. The updated sustainability index is a holistic approach to define the
sustainability for each water user. The structure of the index incorporates tailor-made
parameters that for some water users may be crucial in their water management; the
scaling of the index allows a better display of the results; and the flexibility to use
different index structures in the same system allows the meaningful discrimination of
55
performance parameters for specific water users. The Sustainability Index should be seen
as a Water Resources Integrated Index that summarizes the results of essential or desired
performance criteria for water users, system and environmental requirements.
Other mathematic structures have been evaluated during the present research,
such as arithmetic and harmonic average; in all these different structures tested, the
relative change of the Sustainability Index is preserved when comparing to the reference
scenario. Thus, the importance of the Sustainability Index is its relative change with
respect to a defined reference scenario, which for the Rio Grande/Rio Bravo Basin is the
Baseline Scenario (Chapter 6.1). The advantages of the Sustainability Index proposed in
Equation 3-12 is that makes easier to identify if the water supply for as determined water
users is unsustainable because its value is zero or tend to zero. This characteristic of the
Sustainability Index implies that each performance criteria is considered an essential or
desired characteristic of the water management for that particular user.
3.2.2 By Group
In order to compare groups of water users, the relative sustainability (Loucks
1997) was defined as a weighted average of sustainability indices; expressed as
∑
∈
∈
∗
Equation3‐14
Where Wi is a relative weight for the ith water user, ranging from 0 to 1 and
summing to 1. The relative sustainability is used to calculate the sustainability index for a
group k that contains water users from i to j. If the sustainability of each user is weighted
by its annual water demand, the sustainability index for the kth group is expressed as
56
∑
∈
∈
∗
Equation3‐15
Equation3‐16
where:
∑
∈
∈
For the Rio Grande/Rio Bravo basin, annual water demands are used to calculate
the weights in the relative sustainability (Eq. 3-15). The relative importance of each
variable is reflected in the weights (Drewnowski 1974). One option is not to include
explicit weights by doing an arithmetic average, also called an equal-attribute-based
weighting system (Slottje 1991). Another option is to use explicit weights which can be
obtained through: (a) a formal analysis such as utility theory analysis (Loucks et al. 1997;
Von Neumann and Morgenstern 1974), the method of principal components analysis or
by a hedonic model weighting the attributes according to regression coefficients (Slottje
1991); or (b) based on weights defined by consultations with experts (Gwartney et al.
1996), decision makers (Vigerstol 2002) or by researcher expertise (Giorgi and Mearns
2002). For the Rio Grande/Rio Bravo, weights are obtained through the water demand
(Equation 3-15) considering that: (a) the necessities of the water users and the
environment can be expressed in the water demand value; (b) interviews with authorities
and water users tend to agree with this formulation; and (c) other performance criteria are
functions of the water demand value, i.e., reliability; or the performance criteria are
scaled (normalized) using the water demand, i.e., vulnerability, maximum deficit and
standard deviation. Not all the necessities of the water users are expressed in their water
demand; however, an important part of the water users and environmental concern is
expressed in this value.
57
3.3 INTEGRATION OF RESULTS
Results can be presented in matrix form. The Performance Criteria Matrix (PCM)
contains the results of the M performance criteria for the ith water users (Equation 3-17).
The PCM has ith rows and M columns.
C
,
C
⋮
⋯
⋱
⋯
,
,
C
,
⋮
C
Equation3‐17
,
The Sustainability Index Matrix (SIM) contains the results of the sustainability
index for the ith water users (Equation 3-18). The SIM matrix has ith rows and one
column. Notice that the SIM reduce the M number of columns in the PCM to one column.
Sust
⋮
Sust
,
Equation3‐18
The Relative Sustainability Matrix (RSM) contains the results of the relative
sustainability index for K number of groups. Each group k is integrated of water users
from i to j. Notice that the RSM reduce the number of rows in the PCM to K number of
rows.
.
Rel. Sust
⋮
Rel. Sust
Equation3‐19
Figure 3-1 shows the PCM, SIM and RSM for Group k of water users from i to j,
whose performance criteria C are from m to M. This figure illustrates how the
58
sustainability index matrix (SIM) reduces the number of columns in the performance
criteria matrix (PCM) by calculating a geometric average of the performance criteria.
Similarly, the number of rows in the sustainability index matrix (SIM) is reduced in the
relative sustainability matrix (RSM) by calculating a weighted average of individual
sustainability indices.
C
⋮
C
,
,
⋯
⋱
⋯
C
⋮
C
Sust
,
⋮
→
Sust
,
→
Figure 3-1: Performance Criteria Matrix (PCM), Sustainability Index Matrix (SIM) and
Relative Sustainability Matrix (RSM)
59
Chapter 4 Application: Rio Grande/Rio Bravo Basin
This chapter explains the water management principles of the Rio Grande/Rio
Bravo basin and how the methodology proposed in Chapter 3 has been used for system
requirements (treaty obligations), water users in the US, Mexico and environmental
requirements. First, the international agreements are presented, describing the water
division between the United States and Mexico and defining the sustainability index for
these system requirements. Second, the water allocation system for Mexico and the US is
presented defining the sustainability index for these water users. Finally, the
sustainability index for environmental requirements is defined.
4.1 INTERNATIONAL AGREEMENTS
Two international agreements establish the water division between the United
States and Mexico: the Convention of 1906 and the Treaty of 1944.
4.1.1 Convention of 1906
The 1906 Convention between the United States and Mexico specifies the
allocation of water of the Rio Grande/Rio Bravo from the El Paso/Ciudad Juarez valley to
Fort Quitman, Texas. According to this convention, the United States must deliver 74
million m3/year to Mexico from Elephant Butte dam (IBWC 1906). This water is used to
supply water to irrigation district DR-009 Valle de Juarez. For the United States, water
from Elephant Butte dam is allocated according to the Rio Grande Compact to the
Elephant Butte Irrigation District in New Mexico and the El Paso County Water
Improvement District #1 in Texas with water rights of 542 millionm3/year and 480
millionm3/year, respectively (IBWC DEIS 2003a and 2003b).
60
4.1.2 Treaty of 1944
The 1944 treaty between United States and Mexico specifies the water allocation
for the Rio Grande/Rio Bravo, Colorado and Tijuana rivers (IBWC 1944). Articles 4
though 9 define the Rio Grande/Rio Bravo water allocation for both countries below Ft.
Quitman, Texas. The United States has the ownership of: (1) all the waters reaching the
Rio Grande/Rio Bravo from the Pecos and Devil Rivers, Goodenough Spring, and
Alamito, Terlingua, San Felipe and Pinto Creeks; (2) one third of the flow reaching the
Rio Grande from the six Mexican tributaries Rio Conchos, San Diego, San Rodrigo,
Escondido, Salado and Arroyo Las Vacas, provided that this third shall not be less than
431.721
million m3/year as an average over cycles of 5 consecutive years; and (3) one
half of all other flows not otherwise allotted along the Rio Grande/Rio Bravo. Mexico has
the ownership of: (1) all the waters reaching the Rio Grande from the San Juan and
Alamo Rivers, including the return flows from lands irrigated from these rivers; (2) two
thirds of the flow reaching the Rio Grande/Rio Bravo from the six Mexican tributaries
named above; and (3) one half of all other flows not otherwise allotted occurring along
the Rio Grande/Rio Bravo.
Amistad and Falcon international dams are used to store and manage the water for
both countries and each country has its own storage account in each reservoir. Amistad
dam has a conservation capacity of 3,887 million m3 of which 56.2% belongs to the U.S.
and 43.8% belongs to Mexico. Falcon dam has a conservation capacity of 4,889 million
m3 of which 58.6% belongs to the United States and 41.4% belongs to Mexico. The treaty
cycles mentioned above can expire in less than five years if the U.S. storage in both dams
is filled with water belonging to the United States.
The Mexican water deliveries specified in the treaty must be fulfilled with the
one-third outflow of the six Mexican tributaries listed above. At the end of a 5-year cycle,
61
the delivery from these tributaries is evaluated to determine the accomplishment of the
treaty obligations. If there is a deficit in the treaty delivery, this deficit must be paid in the
following cycle primarily with the one-third outflow of water coming from the six
tributaries and extraordinarily, if the Mexican and the U.S. section of the IBWC agrees,
with the Mexican portion of the six tributaries and with transfers of water from the
Mexican storage in the international dams (IBWC 1969).
The sustainability index proposed for the treaty obligations is:
∗
∗ 1
∗ 1
Equation4‐1
Four out of the six Mexican tributaries delivering water to the treaty are
unregulated rivers (Arroyo Las Vacas, San Diego, San Rodrigo and Escondido). In
addition, there is no defined policy in the two regulated rivers (Rio Conchos and Salado)
to deliver water to meet treaty obligations; in practice, only the gains of the reach
between the most downstream reservoir in each tributary (Luis L. Leon dam in Rio
Conchos and Venustiano Carranza dam in the Rio Salado) and the Rio Grande/Rio Bravo
confluence are left in the river to met the treaty obligations. Sporadically, spills from
these reservoirs will contribute to the delivery of treaty obligations. Thus, in practice, the
treaty obligations are supplied by natural means. Because of this, the standard deviation
criterion ( ) is used to assess the variability of the treaty obligations and to help identify
adaptation policies that reduce the variability of treaty deliveries, providing a more steady
delivery of treaty water by increasing low flows during drought periods and reducing
spills during wet periods. The standard deviation for the treaty obligations (
calculated from the annual deliveries of the 6 Mexican tributaries.
62
) is
4.2 MEXICO
On the Mexican side of the Rio Grande/Rio Bravo, the National Water
Commission “Comisión Nacional del Agua” (CONAGUA) is the federal authority
responsible for water management. CONAGUA carries out water planning and
management along the border according to the accounting of water provided by the
IBWC.
Mexican water demands are characterized by use. In this research are considered
only agricultural, domestic, municipal and other water users, accounting for the 99.2% of
the total Mexican water demand (CONAGUA 2004). The National Waters’ Law of
Mexico “Ley de Aguas Nacionales” establishes the priority for all water uses
(CONAGUA, 2008.a). Municipal and domestic users have the highest priority and two
times their annual water demand must be stored in the reservoirs. Agricultural users are
not guaranteed and their allocation depends on the available storage in the respective dam
that supplies them. Each October, CONAGUA determines the available reservoir storage,
after deducting municipal allocations, evaporation and operation losses (Collado 2002).
Then, a negotiation between CONAGUA and the irrigation districts sets the agricultural
water allocation for the coming water year. Since 2002, CONAGUA has tried to deliver
the users’ annual water concession (legal definition of water rights in Mexico) if there is
enough water in the available storage in the respective reservoirs, if not, a shortage in the
water delivery is negotiated.
The sustainability index proposed for Mexican water users is
∗
∗ 1
63
∗ 1
Equation4‐2
The Rio Grande/Rio Bravo is a naturally water scarce basin (SEMARNAT 2004),
extended and severe periods of drought have occurred in the basin. During the latest
drought (1994-2003), Mexico was not able to deliver the treaty water to the U.S. in two
consecutive cycles of the 1944 treaty: cycle 25 (1992-1997) and cycle 26 (1997-2002). In
order to cover these deficits, extraordinary measures were taken by the authorities, such
as stopping the supply for Mexican irrigations districts 025 Bajo Rio Bravo and 004 Don
Martin for two years (2002 and 2003) and transferring Mexican storage in the
international reservoirs to the U.S. (IBWC 2001 and 2002). These decisions severely
affected Mexican agriculture water users in the basin, almost extinguishing this activity
in the lower part of the basin. Because of this, the Maximum Deficit criterion (
)
is included in the sustainability index for Mexican water users. The aim of this criterion is
to help identify adaptation policies that not only reduce the expected deficit (1
but also the maximum deficit that they may experience (1
)
). Reliability,
Resilience, Vulnerability and Maximum Deficit are calculated based on the annual water
supply to Mexican users.
4.3 UNITED STATES
In the U.S., the Texas Commission on Environmental Quality (TCEQ) is the state
agency in charge of water management in Texas. The Texas Rio Grande Watermaster
Program regulates the U.S. water diversion from Amistad reservoir to the Gulf of Mexico
(TCEQ 2005a). TCEQ performs water planning and management along the U.S. Rio
Grande portion of the river according to the accounting of water provided by the IBWC.
The Texas Water Master allocates water on an account basis (TCEQ 2006)
according to five water use types: irrigation, municipal, mining, industrial and other.
64
Below Amistad reservoir water rights are divided into Type A and B according to the
Texas Watermaster Rules. Municipal and industrial users have the highest priority and
they are guaranteed an amount for each year. The rest of the users are not guaranteed and
their allocation depends on the water remaining in their accounts from the previous year.
Every month the Texas Water Master determines the amount of unallocated water in the
U.S. account of the international reservoirs after the municipal and industrial allocation
has been subtracted. If there is surplus water remaining, it is allocated to agricultural
users of Type A, then Type B, then mining and finally other uses.
The sustainability index proposed for U.S. water users is
∗
∗ 1
∗ 1
Equation4‐3
Similarly to Mexico, agriculture and mining water users in the U.S. suffered
shortages in their water demand during the last drought (1994-2003). Because of this, the
Maximum Deficit criterion (
) is also included in the sustainability index for
U.S. water users. The water management for the U.S. is executed by month; water
planning models used by the TCEQ (Brandes 2004) require that the time-based and
volumetric reliability are calculated in monthly time steps. Thus, reliability, resilience,
vulnerability and maximum deficit for U.S. water users are calculated in monthly time
steps.
65
4.4 ENVIRONMENT
In the Rio Grande/Rio Bravo basin, environmental flows are not considered an
integral part of water management. During the planning, negotiation and distribution of
water in the treaties, environmental needs of native ecosystems were not explicitely
considered (Orive-Alba 1945, Enriquez-Coyro 1976, Collado 2002). In the Convention of
1906 (IBWC 1906), the treaty of 1944 (IBWC 1944) and the Rio Grande Compact
(TCEQ 1938); water distribution and allocation exclusively obeys human requirements,
considering neither environmental flows nor a priority assigned to the environment.
However, this inattention can/may change in the future, in the treaty of 1944 (Article 3)
environmental requirements could be included as a beneficial use; furthermore, the
Article 3 can be modified using a minute to re-order the water use priority in the basin.
Several efforts have been undertaken by individuals, government agencies and
non-governmental organizations to determine the environmental flows required for the
basin (Sandoval-Solis and McKinney 2009). In the Rio Conchos sub-basin, the World
Wildlife Fund estimated the environmental flows at 9 locations (WWF 2006). These
flows are used to evaluate the performance of the environmental requirements.
The sustainability index proposed for the environmental flows is
,
,
∗
,
,
∗ 1
∗ 1
,
Equation4‐4
During droughts the environment suffers to meet its water requirements; usually,
extreme low streamflows happen in these periods affecting the health of aquatic and
riparian ecosystems. For this reason the Maximum Deficits criterion is included in Eq. 44. The Sustainability Index proposed for the environment considers essential to provide
environmental flows frequently (Reliable), that if deficits happen, the expected (166
Vulnerability) and maximum deficits (1-Maximum Deficit) are small, and that the system
recover fast from deficits (Resilient). Since the environmental flows were aggregated
monthly (Chapter 6.2.5), the performance criteria for the environment are calculated
based on the monthly environmental flow supply. Because of the monthly time step
characteristic of the Rio Grande/Bravo WEAP model, daily performance criteria are not
evaluated, such as: a) the daily exceedance duration of a monthly indicator flows (i.e.,
50%, 80% and 90% exceedance percentile flows), b) duration and number of spells of
flows less than low flow threshold (i.e., duration of flows lower than 0.01 m3/s), c)
average recurrence interval of high daily flows (i.e., daily flows with return period of 1.5,
5 and 20 years in natural conditions) (Brizga et al. 2002). Further research is needed to
build a daily time step model to properly assess the supply of environmental requirements
in the basin.
67
Chapter 5 Water Resources Planning Model
A water resources planning model of the Rio Grande/Rio Bravo basin is used to
evaluate the current and proposed water management policies. The Rio Grande/Rio
Bravo WEAP model is a hydrologic planning simulation model that represents the water
management in the basin (Danner et al. 2006). The Water Evaluation and Planning
System (WEAP) (SEI 2010) is used to model water management in the Rio Grande/Rio
Bravo basin. In the first part of this chapter the Rio Grande/Rio Bravo WEAP model is
presented and compared with other planning models already built for the basin. In the
second part of this chapter is described the characteristics of the Rio Grande/Rio Bravo
WEAP model, such as period of analysis, the input data, infrastructure, operation and
model testing. Details of WEAP and its application to other basins can be found in Yates
et al. (2005a and 2005.b) and Purkey et al. (2007).
5.1 INTRODUCTION
Several agencies and institutions have built models of the Rio Grande/Rio Bravo
basin or its sub-basins for different purposes: sediment transport (TAMU 1996),
groundwater interaction (Bartolino and Cole 2002), dispute resolution (Tate 2002), water
availability (Brandes 2003a), water management (Stewart et al. 2004, Gastelum et al.
2009), reservoir operations (US ACE 2004), drought management (Vigestol 2002,
Gastelum 2006), rainfall-runoff response for historic (IMTA 2005) and future climate
change conditions (Ingol-Blanco and McKinney 2008), among others. In this sense, the
Rio Grande/Rio Bravo WEAP model is a water planning model intended to help in the
dispute resolution, policy and decision making as did the OASIS (Tate 2002) and Stella
(Vigerstol 2002) models, for the whole basin and not only for the Rio Conchos (Gastelum
68
2006), but with a solid calibration and validation of the model. The Rio Grande/Rio
Bravo WEAP model is based on a firm understanding of the water allocation rules, water
demands, regulations and international agreements that apply in different regions for both
countries.
5.2 PERIOD OF ANALYSIS
The period of analysis is 60 years, from October 1940 to September 2000. The
Rio Grande/Rio Bravo WEAP model carries out its simulation according to the water
year (October – September), when the water authorities decide the amount of water to be
allocated for each user. This period of analysis contains the historical drought record of
the 1950’s (1947-1957), the drought of the 1960’s (1961-1965), the abundant water
period of the 1970’s and 80’s (1966-1993) and part of the most recent drought of the
1990’s (1994-2007). Hydrological input data, such as, naturalized flow, evaporation,
stream flow data, and reservoir storages etc., are available for this period. The main
source for hydrologic, hydraulic and related data for the model is the Rio Grande/Bravo
geodatabase (Patino-Gomez et al., 2007).
5.3 HYDROLOGIC DATA
The data used in the Rio Grande/Rio Bravo WEAP model comes from different
agencies in both countries. Main tributary headflows and inflows along the reaches were
taken from two sources: (1) the “naturalized stream flow” data for the Rio Grande basin
developed for the TCEQ by the R. J. Brandes Company (2003a) and (2) from the “annual
naturalized flow data” calculated in the Annual Water Availability study for the Rio
Bravo published by CONAGUA (2008.b). A total of 21 headflows and 22 incremental
69
inflows along the reaches are included in the Rio Grande/Rio Bravo WEAP model. The
model contains channel loss factors for the river reaches accounting for conveyance,
evaporation, evapotranspiration and seepage losses (IBWC 2005; CONAGUA 2007; and
Brandes 2003b). Details of the model components, coefficients and performance are
available in Danner et al. (2006).
5.4 WATER DEMANDS
The Rio Grande/Rio Bravo WEAP model includes 216 water demands (Table
5-1). U.S. water demands are divided into five water use types: agricultural, municipal,
mining, industrial and other. Also, below the international reservoirs Amistad and Falcon,
Texas water rights are divided into Type A and B based on the Texas Watermaster
Allocation logic (TCEQ 2005a). U.S. water demands in the model were derived from the
TCEQ (2005b) and the Rio Grande Compact (IBWC DEIS 2003a and 2003b). Annual
demands used in the model correspond to 62% of the full allocation demand (personal
communication, Carlos Rubenstein, Commissioner, TCEQ, October 2009) and these are
disaggregated into monthly values, according to the distributions estimated by TCEQ
(Brandes 2003a).
Mexican water demands are characterized by use. In the model, only agricultural,
municipal and other water users are considered because they represent the 99% of the
total consumptive water use for Mexico (CONAGUA 2004). The priority for all water
users is established in the National Waters’ Law (CONAGUA 2008.a). Mexican water
demands were derived from the public database of water rights (CONAGUA 2004),
which is the official database of CONAGUA. For Mexico, annual water uses for 2004
were disaggregated into monthly values. Return flow factors were derived from TCEQ
70
(2005b), IMTA (Collado, 2002) CONAGUA (CONAGUA 2004), and water users
(CONAGUA 2005, L. R. Caballero, private communication May 2005).
Table 5-1: Water Demands considered in the Rio Grande/Rio Bravo WEAP Model
Water Use
Municipal
Irrigation
Other*
Groundwater
Total
Demands
Mexico
United States
Number
(Million m3/year)
Number
(Million m3/year)
Number
(Million m3/year)
Number
(Million m3/year)
21
731
39
3,881
1
47
35
1,852
23
283
53
3,034**
20
11
21
2,840***
Number
(Million m3/year)
96
6,511
120
6,168
* This category includes Industrial, Mining and Other water uses.
** Full Allocation Demand for U.S. water demands. The current conditions are 62% of the Full Allocation Demand.
*** This value represents an Upper bound on aquifer withdrawal by these water demands.
Due to the large number of individual water users along the river in both
countries, many of the water demands were aggregated in the model. U.S. demands were
aggregated based on use type, i.e., municipal, irrigation, etc, type of water right (A or B)
and location in the basin relative to the river reaches defined by the TCEQ Rio Grande
Watermaster. The Watermaster Rules define thirteen river reaches, referred to as
Watermaster Sections (Brandes 2003a). Similarly, Mexican demands were aggregated
also by type of use and location in the basin. Surface water and groundwater use in both
countries is considered in the model. Most of the semi-formal irrigation districts in
Mexico (called Urderales) and many of the individual water users in the U.S. use
71
groundwater as their main source of water supply. Groundwater is represented in the
model as simple “tanks” for each regional aquifer in the basin.
5.5 INFRASTRUCTURE
There are twenty five reservoirs in the model with a total storage capacity of
approximately 26.3 billion m3 (Danner et al. 2006). Sixteen of the reservoirs are located
in Mexico with a total storage capacity of about 11.4 billion m3; six are in the U.S. with a
total storage capacity of about 3.4 billion m3; and three international reservoirs, Amistad,
Falcon and Anzalduas (weir) with a total storage capacity of about 11.6 billion m3 (CILA
2009).
5.6 OPERATION
The water allocation system represented in the Rio Grande/Rio Bravo WEAP
model follows the allocation of water for Texas according to the Texas Administrative
Code Title 30 Chapter 303 (TCEQ 2006), for Mexico according to the National Waters’
Law (CONAGUA 2008.a), and along the border it follows the international allocation of
water established in the Convention of 1906 (IBWC 1906) and the Treaty of 1944
between Mexico and the U.S. (IBWC 1944). The model contains rules to replicate the
accounting and allocation logic of the 1944 U.S.-Mexico Treaty. This logic includes:
tracking inflows from the treaty tributaries; allocating those flows to the respective
countries; accounting for storage for each country in the international reservoirs;
calculating evaporation losses for each country; accounting of the Mexican treaty
deliveries per year and cycle, and resetting treaty cycles when the international reservoirs
are filled.
72
5.7 MODEL TESTING
Although the model contains inflow data for sixty years, model calibration was
done for 15 years, from October 1978 to September 1993. During this period construction
of most of the basin infrastructure had been completed, including both international
dams. Even though there was no specific water allocation policy in Mexico during this
period, the record of historic diversions exists for almost all of the water users. For
Mexico, historical diversions were provided by CONAGUA (2008.b) and for the U.S.
these data were derived from the IBWC withdrawal records available online (IBWC
2009). This section briefly describes the testing process for the Rio Grande/Rio Bravo
WEAP model which includes the calibration and validation procedures. A complete
description of this process is presented in Danner et al. (2006).
5.7.1 Calibration
In general, two important sets of parameters were used to calibrate the Rio
Grande/Rio Bravo WEAP model: the conveyance losses along the streams and the rules
governing the release of water from the conservation pools of the dams.
At least two sets of conveyance losses factors are available for the Rio
Grande/Rio Bravo basin, one set from CONAGUA (Collado 2002, Aldama 2008) and
other set from TCEQ (Brandes 2003b). The set of conveyance losses that provided the
best model performance is the following: on Mexican streams the CONAGUA
conveyance losses are used; on U.S. streams and along the Rio Grande/Rio Bravo mainstream the TCEQ conveyance losses are used. The decision to use the TCEQ conveyance
losses along the Rio Grande/Rio Bravo stream is supported by the fact that this set
considers the evaporation and plant uptake losses, including the salt cedar effect along the
73
river, as well as the geology and hydrogeology for each reach; the CONAGUA
conveyance losses do not consider these factors.
Regarding the conservation pools of the dams, the conservation storage for all the
U.S. dams is well defined; however, this value varies seasonally for the Mexican and
international dams. For dams in Mexico, it usually varies as follows: the normal
conservation storage is used in the rainy season, June 1st to October 31st; meanwhile a
larger and undefined conservation storage is used for the rest of the year. An historic
analysis of the dam storages was done in order to define the conservation pool value for
each Mexican and international dam.
One of the main uncertainties in the model is the conveyance losses along the
reaches, mostly during drought periods. The conveyance losses provided in the two
available datasets, CONAGUA and TCEQ, are fixed values along the time. These values
were estimated considering normal conditions (Collado 2002, Brandes 2003b). As a
result, under drought periods these values underestimate the losses in the system. Several
runs were done in order to estimate the variation of the conveyance losses as a function of
the hydrologic conditions; however, due to the lack of data during drought periods it was
not possible to obtain this relationship. Further research is needed regarding the
conveyance losses in the basin as a function of the hydrologic conditions. A more
detailed explanation about the calibration process is provided in Danner et al (2006).
5.7.2 Validation
A Historic Scenario was developed to evaluate the accuracy of the model; model
results were compared to historical values for reservoir storage and gauged stream flow.
A 15-year hydrologic period of analysis was used for this scenario (October 1978 to
74
September 1993). This period was selected because both international dams were in
existence and operating. The historic water demands of this period were loaded into the
model and results from streamflows and reservoir storage were compared with the
historic data. Water demands in this period varied from year to year; historical Mexican
demands for municipalities, irrigation districts and private users were provided by
CONAGUA (CONAGUA 2008.b) and the U.S. demands were derived from the IBWC
withdrawal records from all the Water Master Sections (IBWC 2009). Figure 5-1 and
Figure 5-2 show the historic water demands loaded into the model in the Historic
1800
1600
1400
1200
1000
800
600
400
200
Figure 5-1: Historic water supply for U.S. demands
75
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
0
1979
Water Supply (million m3/year)
scenario for the U.S. and Mexico, respectively.
4000
3500
3000
2500
2000
1500
1000
500
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
0
1979
Water Supply (million m3/year)
4500
Figure 5-2: Historic water supply for Mexican demands
The conveyance losses along the streams and the rules governing the releases of
water from conservation pools were adjusted in order to match streamflows at different
stations and reservoir storages given the historic water supplies. Danner et al. (2006)
presents the comparison of the historic and the model values for 12 reservoir storages and
8 streamflow gages. During the calibration and validation process, the storage in the
international reservoirs Amistad and Falcon were used as indicators to evaluate the
performance of the model because: (a) they store the water for each country according to
the treaty of 1944; and (b) both reservoirs are influenced by the water management in the
entire basin. Thus, if there is a problem in the modeling of certain region or with the
water for each country, the storage in the international reservoirs shows it immediately.
Amistad’s inflows depend on the water management in the Conchos and Pecos
basin as well as the water coming from the Devils and Fort Quitman; Amistad’s outflows
depend on the water releases for water users upstream Falcon and transfers of water to
Falcon. Falcon’s inflows depend on the water transfers from Amistad and the water
management in Las Vacas, San Diego, San Rodrigo, Escondido and Salado rivers;
76
Falcon’s outflows depend on the water releases for the lower Rio Grande Valley and the
water coming from San Juan River. Thus, the model can be evaluated using the storage at
these reservoirs. Figure 5-3 and Figure 5-4 show a comparison of the international dam
storage calculated by the model and the historic data for Mexico and the U.S.,
respectively.
100%
80%
60%
40%
US Historic (%)
US Model (%)
20%
Oct-92
Oct-91
Oct-90
Oct-89
Oct-88
Oct-87
Oct-86
Oct-85
Oct-84
Oct-83
Oct-82
Oct-81
Oct-80
Oct-79
0%
Oct-78
Total U.S. Active Storage
Capacity (%)
120%
120%
100%
80%
60%
40%
Mex Historic (%)
Mex Model (%)
20%
Oct-92
Oct-91
Oct-90
Oct-89
Oct-88
Oct-87
Oct-86
Oct-85
Oct-84
Oct-83
Oct-82
Oct-81
Oct-80
Oct-79
0%
Oct-78
Total Mexico Active Storage
Capacity (%)
Figure 5-3: U.S. storage in the international dams; Model versus Historic
Figure 5-4: Mexican storage in the international dams; Model versus Historic
77
Two coefficients are used in the storage at the international reservoir for each
country to evaluate the goodness of fit for the model validation (Legates and McCabe
1999): the coefficient of efficiency (E) shown in Equation 5-1 (Nash and Sutcliffe 1970)
and the coefficient of agreement (d) shown in Equation 5-2 (Willmott et al. 1985). These
coefficients compare the observed values (Ot) against the predicted values (Pt) from the
model at time step t, over n number of total time steps.
∑
1.0
Equation5‐1
∑
∑
1.0
∑
|
| |
|
Equation5‐2
where:
∑
Equation5‐3
The coefficient of efficiency (E) ranges from minus infinity to 1, with higher
values indicating better agreement. The index of agreement (d) varies from 0 to 1 with
higher values indicating a better agreement between the model and the observations
(Legates and McCabe 1999). The coefficients of efficiency for Mexico and the U.S. are
0.825 and 0.805, respectively; meaning that the mean square error (i.e. the squared
differences between the observed and model values) is 17.5% and 19.5% of the variance
in the observed data. The coefficients of agreement for Mexico and the U.S. are 0.953
and 0.945, respectively; meaning that the mean square error is 4.7% and 5.5% of the
potential error (∑
|
|
|
| ). The potential error is the largest value that
can attain for each observation/model simulation pair. In both coefficients, the
difference between the observed and predicted value (in fact, the mean square error) is
78
small compared to the variance or the potential error. Both coefficients show that the Rio
Grande/Bravo WEAP model is adequately representing the water resource system; the
mean square error is less than 20% of the observed variance of the data, and less than 6%
of the potential error.
79
Chapter 6 Water Management Scenarios
In this chapter are described the water management scenarios evaluated for the
Rio Grande/Rio Bravo basin (NHI 2006b). First, the Baseline scenario is defined, which
is the system with no policy implemented (before 2004). Then, the alternative water
management scenarios are described in two groups; scenarios for the upper and lower
basin. This section includes policies already implemented, such as the buyback of water
rights through the PADUA program and improvement in infrastructure through Minute
309; as well as proposed policies, such as groundwater banking and environmental flows
in the Rio Conchos sub-basin. Finally, the Current scenario is defined, which is the
system as it is now, considering the policies already implemented (after 2004). Results of
the no policy scenario (Baseline Scenario) and all the scenarios described in this chapter
are presented in the chapter seven.
6.1 BASELINE SCENARIO
The Baseline scenario is the system without any policy implemented. This
scenario follows the water management principles already explained: the division of
water between the U.S. and Mexico according to the Convention of 1906 and the Treaty
of 1944; in the U.S. according to the Texas Rio Grande Water Master Program; and in
Mexico according to the National Water’s Law. The Baseline scenario is the water
management before 2004. For U.S. water user is considered the 70% of the full allocation
demand; for Mexico is considered the water demand in 2004. The aim of this scenario is
used to evaluate the benefits and negative effects of the proposed policies in the basin.
80
6.2 UPPER BASIN SCENARIOS: RIO CONCHOS SUB-BASIN
For the Rio Conchos sub-basin, the PADUA program and the water conservation
measures described in IBWC Minute 309 are two policies already implemented.
Groundwater banking through the In Lieu method and the delivery of environmental
flows are two policies proposed in this research.
6.2.1 PADUA Program
In 2003, the Mexican Ministry of Agriculture, Livestock, Rural Development,
Fisheries and Food (SAGARPA from its acronym in spanish) made public the PADUA
program (Programa de Adecuación de Derechos de Uso del Agua y Redimensionamiento
de Distritos de Riego) (SAGARPA 2003). The objective of this program is to buy back
water right titles conferred to irrigation districts that under drought conditions would be
impossible or hard to supply from surface water and groundwater, for either economic or
hydrological conditions (SAGARPA-FAO 2005).
Table 6-1: Water Rights Bought Back Under the PADUA Program
Irrigation
District
005 Delicias
090 Bajo Rio
Conchos
Water Source
Surface
Groundwater
Surface
Groundwater
Water Demand
Before PADUA
After PADUA
(1x106 m3/year) (1x106 m3/year)
941.6
850.3
189.0
170.7
85.0
63.7
----Total
Water
Bought Back
(1x106 m3/year)
91.3
18.3
21.3
--130.9
Table 6-2 shows the water demand before and after the implementation of the
PADUA program, as well as the volume of water bought back in DR-005 Delicias and
DR-090 Bajo Rio Conchos (see Figure 6-1). In irrigation district DR-005 Delicias 91.3
81
million m3/year (74,000 acre-feet/year) of surface water rights and 18.3 million m3/year
(14,800 acre-feet/year) of groundwater rights were bought back. In irrigation district DR090 Bajo Conchos 21.3 million m3/year (17,300 acre-feet/year) of surface water rights
were bought back. The total amount of water rights retired under the program was 130.9
million m3/year (106,100 acre-feet/year) from which 112.6 million m3/year (91,300 acrefeet/year) are of surface water and 18.3 million m3/year (14,800 acre-feet/year) are of
groundwater (SAGARPA 2005, SAGARPA 2006 and SAGARPA 2007).
Figure 6-1: Irrigation Districts in the Rio Conchos Basin
Table 6-2 shows the investment when the PADUA program was implemented and
an estimate present value for a policy similar to the PADUA program. From 2004 to
2006, surface and ground water right bought back occurred at $159 and $198 per 1,000
m3, respectively ($2,000 and $2,500 pesos per 1,000 m3 of surface and groundwater
82
rights, respectively; monetary exchange 12.6 pesos per dollar). These cost of surface and
groundwater in the present year (2011) considering an annual interest rate of 6.5% are
$217 and $272 per 1,000 m3, respectively ($2,740 and $3,425 pesos per 1,000 m3 of
surface and groundwater rights, respectively; monetary exchange 12.6 pesos per dollar).
The total investment of this policy in present value is $29.5 million dollars. For this
research, the PADUA program will be used as the initial parameter in the scenarios
related to the permanent buy-back of water rights in the basin.
Table 6-2: Investment in the PADUA Program
Irrigation
District
DR-005
DR-090
Investment
in 2006*
($ Million)
(A)
Investment
in 2011**
($ Million)
(B)
Water
Bought Back
(1x106 m3/year)
( A / B)
Cost per million
of water saved
($ Million)
Surface
14.5
19.8
91.3
0.217
Groundwater
3.6
5.0
18.3
0.272
Surface
3.4
4.6
21.3
0.217
Groundwater
---
---
---
---
Water Source
Total
130.9 0.225 21.5 29.5 3
* $159 and $198 per 1,000 m ($2,000 and $2,500 pesos) of surface and groundwater rights, respectively;
monetary exchange 12.6 pesos per dollar
** $217 and $272 per 1,000 m3 ($2,740 and $3,425 pesos) of surface and groundwater rights, respectively;
annual interest rate 6.5%; monetary exchange 12.6 pesos per dollar
6.2.2 Reduction of DR-005 Delicias to 50,000 hectares
One of the scenarios proposed is the reduction of the agriculture area of irrigation
district 005 Delicias from 90,000 to 50,000 hectare. This reduction goes beyond what was
considered when the 1944 Treaty was signed, since in that time DR-005 Delicias was
considered to be 71,500 ha of agriculture land (IBWC 1946). A linear relationship of the
irrigated area and the water demands was used to obtain the water demand for 50,000 ha.
83
Considering that to supply water for 90,000 ha it is necessary a water demand of
1130.546 million m3/year (917,000 acre-feet/year), in order to supply water for 50,000 ha
is necessary 628.081 million m3/year (509,000 acre-feet/year).
Table 6-3 show the surface and groundwater buybacks, and the investment
required to reduce irrigation district 005 Delicias from 90,000 ha to 50,000 ha. In 2006,
when the PADUA program finished, the buyouts of surface and groundwater rights
occurred at $159 and $198 per 1,000 m3, respectively ($2,000 and $2,500 pesos per 1,000
m3 of surface and groundwater rights, respectively; monetary exchange 12.6 pesos per
dollar). These costs of surface and groundwater in the present year (2011) considering an
annual interest rate of 6.5% are $217 and $272 per 1,000 m3, respectively ($2,740 and
$3,425 pesos per 1,000 m3 of surface and groundwater rights, respectively; monetary
exchange 12.6 pesos per dollar). The investment estimated for this policy is $89 million.
Table 6-3: Water demands for DR-005 Delicias after reduction of the irrigated area to
50,000 ha.
Water
Source
Surface
Groundwater
Total
Water Demand
After PADUA After Reduction (1x106 m3/year)
(1x106 m3/year)
850.3
523.1
170.7
105.0
1021.0
628.1
Water
Bought Back
(1x106 m3/year)
327.2
65.7
392.9
Price *
($ per 1,000 m3)
217
271
Investment
($ Million)
71.2
17.8
89.0
*Monetary Exchange 12.6 pesos per dollar
Recent data for the 2008 water year (Oct/2007-Sep/2008) show that the irrigated
area in DR-005 Delicias was 52,323 hectare with a diversion of 702 million m3 (660
million m3 from the reservoirs and 42 million m3 from groundwater) (CONAGUA 2009).
84
The 2008 water year is the year after the most recent drought (1994-2007) and according
to CONAGUA (2009); this was an average year for agriculture land cultivated,
considering a 39 year time series of data (1970-2008). Similar data is specified in the
technical information card for DR-005 Delicias showing an estimated annual cultivated
area of 49,574 hectare (CONAGUA 2003). These information shows that the proposed
reduction in the irrigated area is reasonable for DR-005 Delicias.
The objective of this policy is to consolidate the irrigated area to a reasonable and
sustainable size that by buying back water rights that are supplied in wet sea
6.2.3 IBWC Minute 309
On July 3rd 2003, the IBWC signed the Minute 309 that specifies a set of water
conservations measures that will be implemented in irrigation districts in the Rio
Conchos basin and the conveyance of the savings to the Rio Grande/Rio Bravo (IBWC
2003). This minute is part of a set of immediate and long-term actions taken in the
drought of 1994-2003 (IBWC 2001 and 2002). The objective of the water conservation
measures is to increase the global efficiencies in irrigation districts DR-005 Delicias, DR090 Bajo Conchos and DR-103 Rio Florido. Basically, there are the two main ideas to
save water. First, reduce the conveyance losses by lining main and lateral canals; and
second, increase the application efficiency on the farms by installing low pressure supply
systems, land leveling, and implementing sprinkler systems, among others (IBWC 2003).
The conveyance of the water savings to the Rio Grande/Rio Bravo is specified to be each
December and January.
In minute 309, the global efficiency is defined as the ratio of the water consumed
to the water extracted from the water sources. The global efficiency is function of the
85
conveyance and application efficiencies; and is expressed through Equation 6-1. Table
6-4 shows the volume extracted from the water sources, the global efficiencies and the
water savings expected for the irrigation districts selected.
∗
Equation6‐1
Table 6-4: Water savings expected after the conclusion of Minute 309
Irrigation District
005 Delicias
090 Bajo Rio Conchos
103 Rio Florido
Total
Baseline
Volume
Efficiency
(1x106 m3/year)
(%)
857
33
96
35
91
33
1044
---
After Minute 309
Volume
Efficiency
(1x106 m3/year)
(%)
514
55
71
47
63
48
648
---
Expected
Savings
(1x106 m3/year)
343
25
28
396
Before the application of Minute 309, for irrigation district DR-005 Delicias the
conveyance efficiency and application efficiency were estimated of 61% and 54%
respectively. After the water conservation measures the conveyance efficiency and
application efficiency are expected of 69% and 80% respectively (Collado 2002;
Caballero 2005). For this policy, this research considers only the water conservation
measures implemented in DR-005 Delicias. Irrigation districts DR-090 Bajo Conchos and
DR-103 Rio Florido has not been considered yet because the available data is not enough
to make acceptable assumptions about the global efficiency. Further research is needed to
determine the conveyance and application efficiencies for DR-090 Bajo Rio Conchos and
DR-103 Rio Florido.
Table 6-5 shows the investment made in 2004 and the required investment in
present value to implement Minute 309. In 2004 the investment in DR-005 Delicias, DR86
090 Bajo Rio Conchos and DR-103 Rio Florido were $108, $9 and $5 million ($1,360,
$110 and $65 million pesos; monetary exchange 12.6 pesos per dollar). These
investments in the present year (2011) considering an annual interest rate of 6.5% are
$168, $14 and $8 million for DR-005, DR-09 and DR-103 respectively ($2,113, $171 and
$101 million pesos, respectively; monetary exchange 12.6 pesos per dollar). The
investment estimated for this policy in the present year is $189 million.
Table 6-5: Investment spent in Minute 309
(A)
(B)
Investment
Investment
Expected
in 2004*
in 2011
Water Savings (B)
Irrigation District
($ Million)
($ Million Pesos)
(1x106 m3/year)
005 Delicias
108
168
343
090 Bajo Rio Conchos
9
14
25
103 Rio Florido
5
8
28
Total
122
396
189
*Monetary Exchange 12.6 pesos per dollar
*Monetary Exchange 12.6 pesos per dollar, Annual interest rate 6.5%
(A/B)
Cost per million
of water saved
($ Million)
0.489
0.543
0.286
0.478
6.2.4 In Lieu Groundwater Banking in the Rio Conchos
In many regions, such as the Rio Grande/Rio Bravo (Wagner and Vaquero 2002),
it has been recognized that surface and ground water must be managed conjunctively
(Pulido-Velazquez et al. 2006) because of their hydraulic and operational interdependence. Conjunctive management of ground and surface water has been studied for
some time (Buras 1963); mostly, as optimizations models for small (Pulido-Velazquez et
al. 2006), medium (Reining et al. 1999) and large scale areas (McPhee et al. 2004).
Groundwater banking is an area that relies on the conjunctive use of surface water and
groundwater.
87
Groundwater banking through the In Lieu method stores natural recharge from
surface water in aquifers. Consider a water user that has a right to two different water
sources: surface water from a reservoir and groundwater from an aquifer. Recharge to a
groundwater bank in the aquifer may take place in wet years, when there is sufficient
surface water to supply the demand (Figure 6-2.a). In this case, aquifer pumping is
stopped and natural recharge accumulates in the bank. The maximum water deposited in
the groundwater bank is equal to the groundwater right.
a) Normal or high available storage in dams;
dams supply all water demand.
b) Low available storage in dams;
aquifer and dams supply water demand.
Figure 6-2: Scheme of the Groundwater Banking through the In Lieu Method
Extraction from the bank takes place in dry years, when there is insufficient
surface water to supply the demand (Figure 6-2.b). In this case, water from the reservoir
is used to supply as much water as it can, and water from the groundwater bank is
pumped to cover the deficit. When modeling this, the groundwater storage is divided in
two accounts: an aquifer account and a groundwater bank account. The aquifer account
tracks the storage that would have been in the aquifer if the groundwater banking did not
88
take place. In contrast, the groundwater bank account tracks the water deposits and
withdrawals from the bank. In Lieu groundwater banking has three main characteristics:
(1) water users that want to use this method must be supplied by at least two different
water sources; (2) the operation of the bank depends on the surface water available to the
water user; and (3) the accumulation in the bank by natural, rather than artificial, means.
Figure 6-3: Scheme of water supply and diversion under the In Lieu groundwater
banking method
Assume that in period t, water is supplied from a combination of surface water
(SWt) and ground water (GWt), and that the conveyance efficiency for surface water
deliveries (including seepage and evaporation losses) is CE (Figure 6-3). The available
surface water (Av_St) in period t is the sum of the available storage in the r-eth reservoir
supplying the user (
(
,
_
,
1, … ,
. This is equal to the reservoir initial storage
1, …, ) minus any required minimum storage (
89
,
1, … , ).
∑
_
_
∑
Equation6‐2
To track the water deposited in and withdrawn from the groundwater bank, the
following three cases are considered:
1. Available surface water exceeds requirement
⁄
_
Equation6‐3
In this case, in lieu groundwater banking is invoked, curtailing groundwater
pumping and providing all water from surface water sources. A deposit of GWt is credited
in the bank.
Equation6‐4
2. Available surface water is more than the surface water demand (plus losses), but less
than total demand
/
⁄
_
Equation6‐5
In this case, water is supplied from both surface and ground water and the bank is
unaffected.
Equation6‐6
3. Available surface water is less than surface water right (plus losses)
_
/
Equation6‐7
In this case, water is supplied from surface water to the extent possible, but there
will be a surface water deficit,
0, that must be covered from a
_
combination of groundwater and withdrawals from the bank.
Equation6‐8
_
90
Since the 1970’s, studies of banking water in the ground have been conducted to
determine the economic and hydraulic feasibility for storing water in the ground and
recovering it when is needed (NHI, 2001). Since then, groundwater banking projects have
been implemented in areas where the water resources are stressed. Successful
groundwater banking programs of include the Semitropic Groundwater Banking project
(SWSD, 2004), the Kern Water Bank (KWBA, 2008) and the Arvin Edison Water
Storage District (NHI, 2001) in the state of California. In all these cases, the groundwater
bankers are irrigation districts with groundwater rights; the programs are supported by
external clients, such as the Metropolitan Water District of Southern California; and they
involve the storage of clients’ surplus of water in wet years in the local aquifers and water
recovery and delivery in dry years. The development of groundwater banks includes the
assessment of hydrogeology and water quality, legal and financial issues, monitoring
programs, third party impacts, as well as proper water planning and management of the
aquifers. An important key aspect for the success is the efficient communication among
the committees that organize the groundwater banks and the groundwater bankers, who
are the owners of the groundwater rights. Unsuccessful programs of groundwater banking
have failed in one or several of the previous characteristics mentioned (NHI, 2001). At
the beginning of the operation of the Drought Water Bank in Butte County, California,
the program was unsuccessful because third parties were affected during the recovery of
banked water. Pumping rules were modified to correct this. The program still operates
with successful results (Coppock and Kreith 1992; WWD 2004).
91
Figure 6-4: Groundwater banking in the Rio Conchos Basin
Irrigation district 005 Delicias (DR-005) is located in the Rio Conchos basin, a
sub-basin in the middle part of the Rio Grande/Rio Bravo basin (see Figure 6-4). DR-005
has a combined surface and ground water concession of 1130.546 million m3 and it is
supplied by two sources, 189 million m3/year from groundwater out of the Meoqui
aquifer and 941 million m3/year from surface water via the La Boquilla and Francisco I.
Madero reservoirs (744 and 197 million m3/year, respectively). The conveyance
efficiency of delivering surface water is estimated to be 80% (Collado, 2002); no
conveyance loss is assumed for delivering groundwater, it is considered that wells are
uniformly distributed along the irrigation district. Further research is needed to determine
conveyance losses from groundwater extraction. Thus, the threshold of available storage
that controls deposits to the groundwater bank is
92
⁄
1,409 million m3
and the threshold to control withdrawals from the bank is
⁄
1,173 million m3.
For DR-005, the available surface water in the system is the sum of the available storage
in Francisco I. Madero and La Boquilla reservoirs. The minimum operating storages for
La Boquilla and F. I. Madero reservoirs are 165 and 8.5 million m3, respectively. The
present research does not estimate the investment to implement a groundwater banking in
DR-005 Delicias, further research is needed to determine this investment.
In order to be initiated and implemented the groundwater banking, policy,
institutional and legal changes are necessary to encourage its creation. According to the
National’s Waters Law of Mexico, water in the bank would belong to CONAGUA
(2008.a). An agreement between CONAGUA and DR-005 Delicias could be undertaken
to implement the groundwater bank. The DR-005 water users would seek permission
from CONAGUA to temporarily interrupt groundwater deliveries and, in exchange, use
surface water, while CONAGUA must ensure the return of the groundwater to the users
in case of drought. The possibility of obtaining an extra amount of water from the bank
during drought periods may encourage groundwater users to switch to this method. For
the In Lieu groundwater banking policy, this research focuses on the physical feasibility
of the overall management policy, this research does not investigate political, institutional
or legal challenges of implementing a groundwater bank or the details of the hydraulic
conditions that may be encountered in the Meoqui aquifer as a result of bank operations;
further research is needed in these area.
6.2.5 Environmental Flows
Due to high water demand, the scarcity of water resources, and the complexity of
water allocation in the Rio Grande/Rio Bravo basin, environmental flows have not been
93
considered as an integral part of the water management in this basin. Important
environmental habitats such as the Big Bend National and State Parks in the U.S., the
Northern Chihuahuan desert, Maderas del Carmen, Ocampo and Cañón de Santa Elena
natural reserves in Mexico are ecologically threatened because of the lack of
environmental water management policies. Historically, the Rio Grande/Rio Bravo basin
has been manipulated in an exclusive human water resource management (EnriquezCoyro, 1976), not considering the environmental needs for the native ecosystems. One of
the policies proposed in this research is to find alternative water management policy that
delivers environmental flows without worsening the water supply of other users in the
basin; the environmental flows calculated for the Rio Conchos are used for this purpose.
Figure 6-5: Environmental Control Points in the Rio Conchos Sub-basin
94
As part of an environmental flow assessment, the World Wildlife Fund made
significant efforts to estimate the environmental flows required to preserve the health of
riparian ecosystems in the Rio Conchos sub-basin. The process began in 2006 with a
workshop of the Building Block Methodology (WWF 2006) and concluded in 2008 with
estimation of the environmental flows for 9 locations along the Rio Conchos basin
(WWF 2008). Figure 6-5 shows the locations where the environmental flows were
determined. The geomorphology, flora and fauna (fish and invertebrates) were considered
to determine the flows necessary to meet the environmental requirements (Tharme and
King 1998). Daily environmental flows for maintenance and drought conditions were
estimated for each control point. In this research, daily flows were aggregated into
monthly values to be declared into the Rio Grande/Bravo WEAP model; thus, monthly
environmental requirements for drought and maintenance conditions were loaded into the
model. Table 6-6 shows the name, stream and annual volume required for each location.
Table 6-6: Environmental Flows in the Rio Conchos Basin
Environmental Flow
Maintenance
Drought
Site
Name
River
(1X106 m3/year)
(1X106 m3/year)
VM1
VM2
VM3
VM5
VM6
VMa
VMb
VMc
Cuchillo Parado
El Potrero
Estación Conchos
San Pedro de Conchos
Agua Caliente
Valle del Rosario
Valle de Zaragoza
Camargo
Conchos
Conchos
Conchos
San Pedro
Conchos
Balleza
Conchos
Conchos
381.5
323.6
27.1
114.2
134.5
548.1
1214.8
50.6
47.7
36.2
14.2
34.1
24.4
236.3
576.6
23.6
VMd
C. Ortíz
San Pedro
60.8
45.3
95
In order to evaluate the hydrologic feasibility of environmental flows in the Rio
Conchos basin, the following methodology has been developed:
1. An evaluation of the environmental flows proposed with the actual water
management policies is done to identify conflict points where environmental
requirements are more threatened.
2. An alternative operation policy is proposed.
3. The alternative operation policy is evaluated to determine if it improves the
environmental requirements and how much this policy affects or benefits other water
users in the basin.
Results from the no policy scenario (Baseline scenario, Chapter 8 Results by
User: Environment) showed that, in recent years, the environmental requirements have
not been met in any of the control points (Sandoval-Solis and McKinney 2009).
Furthermore, results also showed that the critical points are VMc Camargo and VMd. C.
Ortiz. These control points are located just downstream La Boquilla and Francisco I.
Madero dams, respectively. Because of their location an alternative water management
policy is proposed below. An analysis of La Boquilla–Francisco I. Madero reservoir
system was done to decide what kind of environmental flows, maintenance or drought,
needs to be allocated each year to control points VMc and VMd. At the beginning of each
hydrological year, the available surface water in the system
Equation 6-2. In parallel, the annual
_
is estimated through
required to satisfy the i-eth water users
from this reservoir system is estimated, dividing the annual surface water demand
(∑
) by the conveyance losses (CE), as shown in Equation 6-9.
∑
⁄
Equation6‐9
96
If the Groundwater banking policy is implemented jointly with the environmental
flows, the
is expressed as
⁄
∑
Finally, the available storage
_
Equation6‐10
is compared with the
. Based on
this comparison a decision is made:
 If the available storage is larger than the required diversion, the maintenance flow
level is assigned for the environmental flow Q in that year.
If
_
→
Equation6‐11
 If the available storage is less than the required diversion, the drought flow is
assigned for the environmental flow in that year.
If
_
→
Equation6‐12
The philosophy of this policy is the following: if the water users are expecting a
shortage in their water supply, it is reasonable to ask only for the minimum volume of
water for the environment, i.e., the drought flow; on the contrary, if there is enough water
in the reservoir system to supply the water users dependent on this reservoir system, it is
reasonable to ask for the normal flow for the environment, i.e., the maintenance flow. In
this policy is proposed an annual decision to choose whether to provide drought or
maintenance flow; thus environmental monthly flows depend on annual decisions. In
order to estimate a cost of this policy, let’s consider that the environmental flows are
97
obtained through buying back water rights, such as in the PADUA program. The present
cost for buying back 1,000 m3 of surface water rights is $217.47, as estimated in Chapter
6.2.1 ($2,740 pesos per 1,000 m3, monetary exchange 12.6 pesos per dollar). In this
policy, it is necessary to buy 111.4 million m3 of surface water under normal conditions,
50.6 million m3 for VMc Camargo and 60.8 million m3 for VMd C. Ortiz. Thus, the cost
to buy 111.4 million m3 of surface water is $24.2 million ($305.2 million pesos, monetary
exchange 12.6 pesos per dollar). If the water saved through Minute 309 is delivered in an
environmental pattern, there is no cost for this policy.
6.3 LOWER BASIN: THE LOWER RIO GRANDE VALLEY
For the middle and lower Rio Grande Valley the reduction in the water allocation
for U.S. water user along the thirteen Water Master Sections is a policy already
implemented in this region; two policies are proposed in this research, the buyback of
water rights and the improvement in the infrastructure in irrigation district 025 Bajo Rio
Bravo.
6.3.1 Reduction in water allocation for the Water Master Sections
Below the international reservoir Amistad, water in the U.S. is allocated
according to the Texas Rio Grande Watermaster Program (TCEQ 2006). In this program
the stream of the Rio Grande/Rio Bravo has been divided in two regions: the Middle Rio
Grande and the Lower Rio Grande Valley (Figure 6-6). The middle Rio Grande, which is
the region between Amistad and Falcon dams, is divided in 6 reaches; and the Lower Rio
Grande Valley, which is the region from Falcon dam downstream to the Gulf of Mexico,
is divided in 7 reaches. Thus, for operational purposes the TCEQ divided the Rio
98
Grande/Rio Bravo in 13 reaches. In this research Watermaster Section (WMS) reaches 1
to 6 are referred to the ones located in the middle Rio Grande and reaches 7 to 13 are
referred to the ones located in the Lower Rio Grande Valley, as shown in Figure 6-6.
Figure 6-6: TCEQ Water Master Sections
During the last drought (1994-2004) the water supply for the U.S. was
compromised. At the beginning of the drought (1994-1996) the water supply for the
Watermaster Section 8 to 13 agriculture use Type A (WMS 8-13) was on average 78%
(1400 million m3/year – 1’135,000 acre-feet/year) of the full allocation demand (1801
99
million m3/year – 1’460,000 acre-feet/year). For the rest of the drought (1997-2004), the
water supply was on average 53% (950 million m3/year – 770,000 acre-feet/year) of the
full allocation demand (IBWC 2009). This uncertainty in the water supply provoked the
75th Texas Legislature to order a study (Brandes 2004) that defined the water availability
and the water use limits and vulnerabilities of the system (TWDB 2001). As a result, the
“Current Allocation” for U.S. water users other than municipal, domestic and industrial
was set at 70% of the full allocation demand (TCEQ 2007). The current allocation has
been further reduced to 62% of the full allocation demand (personal communication,
Carlos Rubenstein, Commissioner, TCEQ, October 2009). In this research is evaluated
this reduction in the water allocation, no investment is associated with these water
management policy.
6.3.2 Buy Back of Water Rights in DR-025 Bajo Rio Bravo
As a proposed policy, in this research is evaluated the hypothetical scenario that
water rights are bought back in DR-025 Bajo Rio Bravo, located in the Lower Rio
Grande Valley (see Figure 6-7). Data from DR-005 Delicias is used as a reference to
propose the volume of water rights bought back and the investment required in DR-025
Bajo Rio Bravo. Considering that the volume of surface water rights bought back in DR005 Delicias is 91.3 million m3/year (74,000 acre-feet/year), for DR-025 Bajo Rio Bravo
is proposed a volume of 100 million m3/year (81,000 acre-feet/year) of surface water
rights bought back. As shown in Table 6-2 of Chapter 6.2.1, the cost per million of water
saved is $0.217 million for DR-005 Delicias in 2011, considering an annual interest rate
of 6.5% from 2006 to 2011 ($2,740 pesos per thousand cubic meters; monetary exchange
$12.6 pesos per dollar). Consequently, for the proposed volume of 100 million m3 of
100
surface water rights to be bought back in DR-025 Bajo Rio Bravo at a cost of $0.217 per
million cubic meters saved, the total investment required to implement this policy is
$21.7 million, ($274 million pesos, monetary exchange $12.6 pesos per dollar), see
Table 6-7.
Table 6-7: Estimated investment to buy-back of water rights for DR-025 Bajo Rio Bravo
Surface Water
Buy-Back
(1X106 m3/year)
Irrigation District
025 Bajo Rio Bravo
Cost per million
of water bought-back
($ Million)*
100
Investment
($ Million)
0.217
21.7
* $217 per 1,000 m of surface water bought back ($2,740 pesos); annual interest rate 6.5%;
monetary exchange 12.6 pesos per dollar. Cost derived in Chapter 6.2.1, Table 6-2
3
Figure 6-7: Lower Rio Grande Valley
101
The proposed volume of water rights to be bought back (100 million m3/year 81,000 acre-feet/year) is reasonable since in DR-005 Delicias a similar amount of surface
water rights has already been bought back. In addition, Zatarain et al (2005) estimated
that about 14% of the irrigated area in DR-025 Bajo Rio Bravo is susceptible to salinity
problems, and thus this area is susceptible to be bought back from the irrigation district.
Legally, this scenario is feasible because the rules of the PADUA program considered as
possible recipients of this program, users with water rights from DR-025 Bajo Rio Bravo
(SAGARPA 2003).
6.3.3 Improvement in Infrastructure at DR-025 Bajo Rio Bravo
As a proposed policy, in this research is evaluated the improvement in the
infrastructure of irrigation district DR-025 Bajo Rio Bravo. Data from DR-005 Delicias is
used as a reference to propose the increase in conveyance, application and global
efficiencies for DR-025 Bajo Rio Bravo. According to minute 309, the global efficiency
for DR-005 increased 22% (from 33% to 55%) and the application efficiency increased
26% (from 54% to 80%) (IBWC 2003). These increments in the application and global
efficiencies are used to estimate a similar improvement in the infrastructure of DR-025
Bajo Rio Bravo. Table 6-8 shows that the volume of water saved is 427 million m3/year
(346,000 acre-feet/year) due to an increase in the global efficiency of 22% (from 39% to
61%), in the application efficiency of 26% (from 54% to 80%) and in the conveyance
efficiency of 4% (from 73% to 77%); considering that the actual extraction of DR-025
from Falcon dam is estimated as 1184 million m3/year (960,000 acre-feet/year) (Collado
2002). Equation 6-1 is used to determine the conveyance efficiency given the global and
application efficiencies.
102
Table 6-8: Proposed improvements in the conveyance, application and global efficiencies
for DR-025 Bajo Rio Bravo
Extraction
Volume
(1X106 m3/year)
1184
757
427
Conveyance
Efficiency
(%)
73%
77%
Water Saved
Application
Volume
(1X106 m3/year)
860.54
580.87
Application
Efficiency
(%)
54%
80%
Consumed
Use
(1X106 m3/year)
464.69
464.69
Global
Efficiency
(%)
39%
61%
Similar actions as the ones executed in DR-005 Delicias must be applied in DR025 Bajo Rio Bravo to achieve this increment in the global efficiency, such as reducing
the conveyance losses by lining main and lateral canals and increasing the application
efficiency on the farms by installing low pressure supply systems, land leveling, and
implementing sprinkler systems, among others actions.
Table 6-9: Investment to improve the infrastructure in DR-005 Delicias
Cost per million
Water Saved
of water saved
Investment
Irrigation District
(1X106 m3/year)
($ Million)*
($ Million)
025 Bajo Rio Bravo
427
0.489
209
* Investment in DR-005 Delicias in 2004: $108 million; water saved: 343 million m3. Considering
a 6.5% annual interest rate; investment in 2011: $168 million. Cost per million of water saved:
$0.489 million ($168 million / 343 million m3 of water saved); monetary exchange 12.6 pesos per
dollar. Cost derived in Chapter 6.2.3, Table 6-5
In order to estimate the investment needed to implement these measures in DR025 Bajo Rio Bravo, data from DR-005 Delicias is used. The estimated cost per million
of water saved in DR-005 Delicias in present value is $0.489 million ($6.2 million pesos
per million of water saved, monetary exchange 12.6 pesos per dollar ) (see Chapter 6.2.3:
Table 6-5). This value is used as a guide to estimate the investment for this policy. Thus,
if the water expected to be saved in DR-025 Bajo Rio Bravo is 427 million m3/year, the
103
investment necessary to save this amount of water is $196.0 Million dollars ($2,470
million pesos of investment, monetary exchange 12.6 pesos per dollar) (Table 6-9).
This scenario is evaluated in two variations: (1) considering that the investment is
fully provided by Mexico, in which case, the water saving are used by DR-025 Bajo Rio
Bravo and (2) considering that half of the investment is provided by the U.S. and half by
Mexico, in which case the water savings are divided between DR-025 Bajo Rio Bravo
and Water Master Section 8 to 13 (WMS 8-13).
6.4 CURRENT SCENARIO
The Current scenario considers the policies that have been implemented in the
basin, since 2004. Three policies have been already implemented:
a) The buyback of water rights through the PADUA program,
b) The improvement in the infrastructure due to IBWC Minute 309, and
c) The reduction in the water allocation for Water Master Sections’ users in
the U.S.
The Current scenario represents the system as it is actually working.
104
Chapter 7 Scenarios Results
This chapter presents the results of the scenarios described in Chapter 6 using the
methodology proposed in Chapter 3 and 4 with the water resources planning model
described in Chapter 5. First, an initial set of scenarios is listed and briefly described.
These scenarios are the policies presented in Chapter 6 or basic combinations of these.
Second, results from these basic scenarios are shown. An analysis of the results is done to
identify the benefits and worsening that each scenario represent to the system. Third,
from the previous analysis a set of winner scenarios is identified in order to define the
“Meta-scenarios”, which are scenarios integrated of policies that promote benefits to the
water resources system.
7.1 SCENARIOS
The scenarios evaluated in this research are listed in Table 7-1. The results from
these scenarios are analyzed in order to identify the benefits or worsening they represent
to the system. Some basic combinations are also analyzed to evaluate their results
working together. Results from the upper and lower basin (LRGV – Lower Rio Grande
Valley) scenarios help us identify which combinations may lead us to winner scenarios
called “Meta-scenarios”.
105
Table 7-1: List of scenarios for the Rio Grande/Rio Bravo Basin
Scenario Description Baseline Water management before any policy was implemented (<2004). For the U.S. water rights are 70% of the full allocation demand and for Mexico is the demand in 2004. I Buy Back of water rights according to the PADUA program. Reduction of the water demand in DR‐005 Delicias and DR‐090 Bajo Rio Conchos due to the buyback of water rights. II Groundwater Banking in DR‐005 Delicias. Conjunctive use of surface water and groundwater to supply the water demand for DR‐005 Delicias. I + II Buy Back of water rights plus groundwater banking in DR‐005 Delicias. Evaluation of these policies working together in DR‐005. III Improvement in infrastructure due to Minute 309 in DR‐005 Delicias. Improvement in the conveyance and application efficiencies due to the measures proposed in Minute 309. The water savings are conveyed to the Rio Grande/Rio Bravo each December and January. IV Environmental flows in the Rio Conchos Sub Basin. Intentional delivery of water from La Boquilla and Francisco I. Madero reservoirs to meet environmental requirements. III + IV Improvement in infrastructure due to Minute 309 in DR‐005 Delicias plus the delivery of the water savings in an environmental pattern. I (LRGV) Buy Back of water rights in DR‐025 Bajo Rio Bravo who is located in the Lower Rio Grande Valley (LRGV). III (LRGV) Improvement in the infrastructure in DR‐025 Bajo Rio Bravo. Improvement in the conveyance and application efficiencies of DR‐025. I + III (LRGV) Buy Back of water rights plus improvement in the infrastructure of DR‐025 Bajo Rio Bravo. III (LRGV) Shared Improvement in the infrastructure in DR‐025 Bajo Rio Bravo and sharing of the savings with WMS 8‐13. This policy considers that both irrigation districts made the investment for the improvements and thus, share the water saved. V(LRGV) Reduction in the water demand of WMS 8‐13 from 70% to 62% of the full allocation demand. 106
7.1.2 Results by User
This section presents the results for selected water users that are considered
relevant in the basin: (a) DR-005 Delicias, the biggest water user in Mexico; (b) DR-025
Bajo Rio Bravo, the biggest water user of Mexico in the Lower Rio Grande Valley; (c)
Water Master Section 8-13 Agriculture use A (WMS 8-13), the biggest water users in the
U.S; (d) Treaty Obligations, the delivery of water from Mexico to the U.S. according to
the 1944 Treaty; and (e) environmental control point VMc Camargo, control point
located below La Boquilla reservoir whose environmental flows have the worst
performance in the baseline scenario.
7.1.2.1 DR-005 Delicias
Irrigation District DR-005 Delicias has a combined surface and ground water
concession of 1,131 million m3 and it is supplied by two sources, 189 million m3/year
from groundwater out of the Meoqui aquifer and 942 million m3/year from surface water
via La Boquilla and Francisco I. Madero reservoirs (744 and 197 million m3/year,
respectively). Table 7-2 shows the sustainability index results for total, surface and
groundwater demands. Results for the LRGV scenarios are not presented for brevity
reasons since these results do no change with respect of the Baseline scenario. Figure 7-1
shows the sustainability index and the differences “Δ(Criteria)” of the performance
criteria considered for this water user with respect of the Baseline scenario: Reliability,
Resilience, 1-Vulnerability and 1-Max. Deficit. These Δ’s help identify which
performance criteria improve due to the policy implemented.
Results show that the buyback of water rights through the PADUA program (I)
and the groundwater banking (II) improve the water management for DR-005 Delicias.
The combination of the previous two policies (I+II) provides the best results for this
107
water user. Also, results show that the improvement in infrastructure (III) and the
delivery of environmental flows (IV) from La Boquilla and Francisco I. Madero
reservoirs worse its water management.
Table 7-2: Sustainability Index for DR-005 Delicias, Baseline and Scenarios
Sustainability Index/Δ (Criterion) (%)
Total
Surface Water
Groundwater
Demand
Sust.
Demand
Sust.
Demand
Sust.
Scenario
(1X106 m3/year)
(%)
(1X106 m3/year)
(%)
(1X106 m3/year)
(%)
Baseline
1130.5
21
941.6
16
189.0
35
I
II
1021.0
1130.5
24
24
850.3
941.6
18
18
170.6
189.0
38
39
I + II
III
IV
1021.0
855.5
1130.5
25
9
20
850.3
666.5
941.6
20
30
15
170.6
189.0
189.0
39
1
34
III + IV
855.5
6
666.5
15
189.0
0
40%
30%
20%
21%
24%
25%
24%
20%
9%
10%
6%
0%
-10%
Baseline
I
II
I + II
III
IV
III + IV
-20%
-30%
-40%
-50%
Sust. (%)
Δ(Rel) (%)
Δ(1-Vul) (%)
Δ(1-Max. Def) (%)
Δ(Res) (%)
Figure 7-1: Sustainability Index and Δ(Criterion) of DR-005 Delicias
108
7.1.2.2 DR-025 Bajo Rio Bravo
Irrigation district DR-025 Bajo Rio Bravo has water concession of 861 million
m3/year supplied from surface water of Falcon reservoir. Table 7-3 shows the
sustainability index results for this water user. Results for all scenarios are shown because
it is located in the lower part of the basin and any change in the water allocation policy
impacts its water supply. Figure 7-2 shows the sustainability index and the differences
(Δ’s) of the performance criteria considered for this water user with respect of the
Baseline scenario: Reliability, Resilience, 1-Vulnerability and 1-Max. Deficit.
For upper basin scenarios, results show that none of the scenario harms the water
management for DR-025. Three scenarios in the upper basin benefits DR-025: (1) the
buyback of water rights due to the PADUA program (I), (2) the combination of the
PADUA program and the groundwater banking (I+II) , and (3) Minute 309 plus the
delivery of the savings in an environmental pattern (III+IV).
For lower basin scenarios, all the scenarios improve the water supply for DR-025.
In any of the cases were improvements in the infrastructure is considered ( III(LRGV),
I+III(LRGV) and III(LRGV) Shared), the water supply improves. Notice that as a side
effect of the reduction of the water demand in WMS 8-13 (V), DR-025 is slightly
benefited from this policy. Also, the buyback of water rights in DR-025 ( I(LRGV) )
improves its water supply.
109
Table 7-3: Sustainability Index for DR-025 Bajo Rio Bravo, Baseline and Scenarios
Sustainability Index
Scenario
3
(1X10 m /year)
(%)
Baseline
I
II
I + II
III
IV
III + IV
I (LRGV)
III (LRGV)
861
861
861
861
861
861
861
761
581
48%
52%
49%
52%
50%
50%
52%
52%
71%
I + III (LRGV)
III (LRGV) Shared
514
581
100%
52%
V(LRGV)
861
49%
100%
52%
Δ(Rel) (%)
Δ(1-Vul) (%)
52%
49%
V(LRGV)
III
52%
III (LRGV)
Shared
I + II
Sustainability (%)
Δ(Res) (%)
Δ(1-Max. Def) (%)
50%
I + III (LRGV)
50%
III (LRGV)
52%
I (LRGV)
49%
III + IV
52%
IV
48%
II
71%
I
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
6
Baseline
Sustainability Index / Δ(Criterion) (%)
Demand
Figure 7-2: Sustainability Index and Δ(Criterion) of DR-025 Bajo Rio Bravo
110
7.1.2.3 Water Master Section 8-13
Irrigation districts Water Master Section 8 to 13 Agriculture A (WMS 8-13) has
full allocation demand of 1801 million m3/year and it is supplied from surface water of
Falcon reservoir. In 2002, according to the TCEQ (TCEQ 2007), the current allocation
demand was set to 70% of the full allocation demand, 1261 million m3/year. This
percentage is used in the Baseline scenario. Table 7-4 shows the sustainability index
results for its water demand. Similarly to DR-025, results for all scenarios are shown
because this water user is located in the lower part of the basin and any change in the
water allocation policy impacts its water supply. Figure 7-3 shows the sustainability
index and the differences (Δ’s) with respect of the Baseline scenario.
For upper basin scenarios, results show the buyback of water rights through the
PADUA (I) program and the improvement in infrastructure due to Minute 309 (III) affect
the water management for WMS 8-13. The rest of the scenarios on the upper basin do not
harm or improve the water management for this user. In fact, two scenarios in the upper
basin improves its water management: the PADUA program plus the groundwater
banking (I+II) and Minute 309 delivering the saving in an environmental pattern (III+IV).
For lower basin scenarios, all of them improve the water supply for WMS 8-13.
All the scenarios promoting a more conservative and sustainable water management in
DR-025 Bajo Rio Bravo improved the water supply for WMS 8-13 (I(LRGV),
III(LRGV), I+III(LRGV) and III(LRGV)Shared). The scenario that provides most
benefits is the improvement in the infrastructure of DR-025 and sharing the water saved.
111
Table 7-4: Sustainability Index for WMS 8-13, Baseline and Scenarios
32%
30%
33%
35%
29%
32%
35%
35%
40%
39%
41%
V(LRGV)
1117
39%
Sustainability (%)
Δ(1-Vul) (%)
Δ(Rel) (%)
Δ(1-Max. Def) (%)
39%
35%
I (LRGV)
35%
III + IV
32%
IV
III
29%
I + II
30%
35%
40%
Δ(Res) (%)
41%
Figure 7-3: Sustainability Index and Δ(Criterion) of WMS 8-13
112
39%
V(LRGV)
1261
1261
1261
1261
1261
1261
1261
1261
1261
1261
1261
III (LRGV)
Shared
Baseline
I
II
I + II
III
IV
III + IV
I (LRGV)
III (LRGV)
I + III (LRGV)
III (LRGV) Shared
I + III (LRGV)
(%)
III (LRGV)
(1X10 m /year)
II
32%
Scenario
33%
6
Sustainability Index
3
I
50%
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
Baseline
Sustainability Index / Δ(Criterion) (%)
Demand
7.1.2.4 Treaty Obligations
According to 1944 Treaty, Mexico has to deliver 431.721 million m3/year as an
average over cycles of 5 consecutive years from one third of the water reaching the Rio
Grande/Rio Bravo of 6 Mexican tributaries: Conchos, Las Vacas, San Diego, San
Rodrigo, Escondido and Salado. The treaty cycles can expire in less than five years if the
U.S. storage in both dams is filled with water belonging to the United States.
Table 7-5 shows the sustainability index results for the Treaty Obligations.
Results are presented for all scenarios because any change in the water management of
the basin affects the meeting of this international agreement. Figure 7-4 shows the
sustainability index and the differences (Δ’s) of the performance criteria considered for
this water user with respect of the Baseline scenario: Reliability, Resilience, 1Vulnerability and 1-Std. Deviation.
None of the scenarios, neither in the upper nor the lower basin, affect the delivery
of the treaty obligations. For upper basin scenarios, Minute 309 scenarios promoting the
improvement in infrastructure (III and III+IV) benefit the most the treaty obligations.
For lower basin scenarios, also the scenarios related with the improvement of
infrastructure (III(LRGV) and III(LRGV)Shared), in this case of DR-025 Bajo Rio
Bravo, promote benefits for the treaty obligations. Also the reduction in the water
demand of WMS 8-13 ( V(LRGV) ) improves the water management of the treaty
obligations which means that the treaty obligations are not only function of the water
delivered from Mexico to the U.S. but also to the water use in the U.S.
113
Table 7-5: Sustainability Index for Treaty Obligations, Baseline and Scenarios
6
70%
60%
51%
Sustainability Index
3
Scenario
(1X10 m /Cycler)
(%)
Baseline
I
II
I + II
III
IV
III + IV
I (LRGV)
III (LRGV)
I + III (LRGV)
III (LRGV) Shared
2159
2159
2159
2159
2159
2159
2159
2159
2159
2159
2159
51%
58%
52%
63%
69%
52%
64%
51%
58%
51%
66%
V(LRGV)
2159
59%
80%
58%
63%
69%
52%
52%
66%
64%
51%
58%
50%
59%
51%
40%
30%
20%
10%
Figure 7-4: Sustainability Index and Δ(Criterion) of Treaty Obligations
114
V(LRGV)
III (LRGV)
Shared
I + III (LRGV)
III (LRGV)
III + IV
III
IV
Δ(Rel) (%)
Δ(1-Vul) (%)
I (LRGV)
Sustainability (%)
Δ(Res) (%)
Δ(1-Std. Deviation) (%)
I + II
II
I
0%
Baseline
Sustainability Index / Δ(Criterion) (%)
Demand
7.1.2.5 Environment
The environmental flows for 9 control points located in the Rio Conchos basin
has been defined using the Building Block method (Chapter 6: Water Management
scenarios, Upper basin:: Environmental flows) (WWF 2006). Here, for purpose of
brevity, only results from control point VMc Camargo are presented (Table 7-6 and
Figure 7-5) because this point has the worst performance of all control points in the
Baseline scenario. This control point is used to exemplify the use of the sustainability
index for environmental requirements. Results for the LRGV scenarios are not presented
because they are the same as the Baseline scenario results.
Results show that scenarios related with Minute 309 (III and III+IV) and with the
delivery of water to the environment (IV) benefit the environmental requirements for
VMc Camargo. Specifically, scenario III+IV which delivers the water savings of Minute
309 in an environmental pattern provides the largest benefits to the environment. In this
scenario the timing of the water savings’ delivery is modified to provide benefits to the
environment. Also notice that the scenarios related to buyback of water rights and
groundwater banking worse the environmental water supply. Results for the rest of the
control points are similar to VMc.
Table 7-6: Sustainability Index for environmental control point VMc Camargo, Baseline
and Scenarios
Demand
6
3
Sustainability Index
Scenario
(1X10 m /year)
(%)
Baseline
I
II
I + II
III
IV
III + IV
23
23
23
23
23
23
23
24%
22%
22%
21%
39%
79%
88%
115
Sustainability Index / Δ(Criterion) (%)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
88%
79%
39%
24%
22%
22%
21%
Baseline
I
II
I + II
Sustainability (%)
Δ(Res) (%)
III
IV
III + IV
Δ(Rel) (%)
Δ(1-Vul) (%)
Figure 7-5: Sustainability Index and Δ(Criterion) of environmental control point VMc
Camargo
7.1.3 Results by Group
The relative sustainability index (Equation 3-15) is used to summarize the results
for water users in the basin. Four groups of interest have been identified in the Rio
Grande/Rio Bravo basin:
1. Rio Grande/Rio Bravo –includes all water users in the basin: U.S. and
Mexican anthropogenic water users, treaty obligations and environmental
requirements;
2. United States – includes all water users in the U.S.;
3. Mexico - includes Mexican water users and the treaty obligations; and
4. Environment – includes the environmental requirements in the Conchos
basin
116
7.1.3.1 Rio Grande/Rio Bravo
The relative sustainability index for all the scenarios analyzed and the Baseline
scenario is shown in Figure 7-6. For the upper basin scenarios, two scenarios provide
more benefits than any other: (1) buyback of water rights through the PADUA program
coupled with groundwater banking in DR-005 Delicias (I+II) and (2) the improvement in
infrastructure due to Minute 309 with the delivery of the savings in an environmental
pattern (III+IV). These scenarios include two policies already implemented (PADUA and
Minute 309) and two policies proposed (groundwater banking and environmental flows).
For the lower basin scenarios, all the scenarios related with the improvement in
infrastructure
of
DR-025
Bajo
Rio
Bravo
(III(LRGV),
I+III(LRGV)
and
III(LRGV)Shared) provide benefits to the water management in the basin. In addition, the
rest of the scenarios in this part of the basin ( I(LRGV) and V(LRGV) ) also provide
benefits to the water management.
Upper Basin
47.5%
45.0%
42.5%
Lower Basin
46%
46%
43%
42%
40%
41%
45%
46%
47%
43%
42%
42%
40.0%
37.5%
Figure 7-6: Relative Sustainability for the Rio Grande/Rio Bravo
117
V(LRGV)
III (LRGV)
Shared
I + III (LRGV)
III (LRGV)
I (LRGV)
III + IV
IV
III
I + II
II
I
35.0%
Baseline
Relative Sustainability (%)
50.0%
7.1.3.2 United States
Figure 7-7 shows the relative sustainability index for the United States water
users’ group. For upper basin scenarios, two scenarios provide benefits: (1) buyback of
water rights through the PADUA program coupled with groundwater banking in DR-005
Delicias (I+II) and (2) the improvement in infrastructure due to Minute 309 with the
delivery of the savings in an environmental pattern (III+IV). A better management in the
upper basin leads to more water available in the whole basin for different water users.
Notice that the combined policies in the upper basin provides benefits to water users in
the U.S. (I+II and III+IV). For lower basin scenarios, all scenarios provide benefits for
U.S. water users. The scenarios related with improvement of infrastructure of DR-025
Bajo Rio Bravo ( III(LRGV), I+III(LRGV) and III(LRGV)Shared ) provide the most
benefits for U.S. water users. This is because more water is stored in the international
reservoirs, Mexican storage capacity fills more frequently and during spilling, all the
inputs are accounted to the U.S. and all the spills accounted to Mexico, according to the
Upper Basin
Lower Basin
42% 43%
39% 39% 39%
39%
36%
Figure 7-7: Relative Sustainability for the United States
118
V(LRGV)
III (LRGV)
Shared
I + III
(LRGV)
III (LRGV)
I (LRGV)
33%
III + IV
III
31%
IV
33%
I + II
32%
II
33%
I
50.0%
47.5%
45.0%
42.5%
40.0%
37.5%
35.0%
32.5%
30.0%
Baseline
Relative Sustainability (%)
provisions of the 1944 treaty.
7.1.3.3 Mexico
Figure 7-8 shows the relative sustainability index for Mexico water users’ group.
For upper basin scenarios, three scenarios provide benefits: (1) the PADUA program
coupled with groundwater banking in DR-005 Delicias (I+II) because it improves the
water management of DR-005; (2) improvements in the infrastructure due to Minute 309
because it improves the treaty obligations and (3) Minute 309 with the delivery of the
savings in an environmental pattern (III+IV) because it improves the treaty obligations
and the environmental requirements. For lower basin scenarios, the scenarios related with
improvement of infrastructure of DR-025 Bajo Rio Bravo ( III(LRGV), I+III(LRGV) and
III(LRGV)Shared ) provide the most benefits for Mexico’s water users. The reduction in
the water demand of DR-025 improves the water management of this water users’ group.
Notice that the reduction in the water demands for the U.S. also provides benefits for
Mexico.
Upper Basin
48%
Lower Basin
48%
47%
47.5%
48%
46%
45.0%
45%
43%
42.5%
47%
45%
43%
43%
42%
Figure 7-8: Relative Sustainability for Mexico
119
V(LRGV)
III (LRGV)
Shared
I + III (LRGV)
III (LRGV)
I (LRGV)
III + IV
IV
III
I + II
II
I
40.0%
Baseline
Relative Sustainability (%)
50.0%
7.1.3.4 Environment
Figure 7-9 shows the relative sustainability results for environmental
requirements group in the Conchos sub-basin. Only results for upper basin scenarios are
presented because results for the lower basin do not change with respect of the Baseline
scenario. Two scenarios provide most benefits: (1) delivering environmental flows to the
system (IV); and (2) Minute 309 with the delivery of the savings in an environmental
pattern (III+IV). On the contrary, the rest of the scenarios aggravate the environmental
conditions. Two scenarios negatively affect the most the environment: (1) the PADUA
program coupled with groundwater banking in DR-005 Delicias (I+II) because it reduces
the variability in the hydrographs required for the environment; and (2) Minute 309
because it simply delivers the water savings in an arbitrary pattern (December and
January). These results show that redistributing the delivery of the savings of Minute 309
in an environmental pattern can improve the environmental conditions at the Rio
Conchos sub-basin.
Relative Sustainability (%)
100%
93%
90%
81%
80%
70%
60%
56%
54%
55%
53%
50%
49%
40%
Baseline
I
II
I + II
III
IV
III + IV
Figure 7-9: Relative Sustainability for Environmental requirements group in the Rio
Conchos sub-basin
120
7.1.4 Summary of Results
For the upper basin, two scenarios have been identified to provide benefits for
most of the water system:
 Scenario I + II - Buyback of water rights through the PADUA program
coupled with groundwater banking in DR-005 Delicias. This scenario
provides the most benefits for DR-005 Delicias in the upper basin
 Scenario III + IV - Improvement in infrastructure due to Minute 309 with
the delivery of the savings in an environmental pattern. This scenario
provided a good balance of benefits for the environment and treaty
obligations.
This policy combination is intended to improve the water management of DR-005
Delicias, the treaty obligations and the environment, which so far has been neglected in
the whole basin. The aim is to counteract the negative effects on the environment of
scenario I+II with scenario III+IV which improves the environment and the treaty
obligations.
For the lower basin, all the scenarios provided benefits to the system; however,
two scenarios provide more benefits to the system:
 Scenario III (LRGV) Shared – Improvement in the infrastructure of DR025 Bajo Rio Bravo and sharing of the water savings with Water Master
Section 8-13. This scenario improves the water management for both
water users and the treaty obligations.
 Scenario I + III (LRGV) – Buyback of water right and improvement in the
infrastructure of DR-025 Bajo Rio Bravo. This scenario improves the
water management. This scenario also improves the water management for
WMS 8-13 and the treaty obligations.
121
These lower basin scenarios promote benefits for water users in both countries
and the treaty obligations.
122
Chapter 8 Meta-scenarios Results
This chapter presents the results of Meta-scenarios integrated of policies that
improve the water management in the system identified in Chapter 7. Meta-scenarios are
combination of basic policies that provide benefits to water users, treaty obligations and
environmental requirements. First, two meta-scenarios are defined and described.
Second, results are shown for individual and groups of water users. These results are
compared with the Baseline and Current scenarios. Third, results from the Current,
Baseline and the meta-scenarios are displayed geographically in order to identify regions
at risk and regions that are benefited from the policies proposed. Forth, conclusions are
derived from the results, which include policies to be applied immediately and in the
short term to improve the water management in the Rio Grande/Rio Bravo basin.
8.1 DEFINITION
Meta-scenarios are scenarios integrated of policies that provide benefits to the
system. The Baseline scenario was used, as a point of comparison, to identify policies (or
combination of policies) that improves the water management of the system. The
Baseline scenario represents the system before any policy was implemented (<2004) and
it helps quantifying the benefits and worsening due to any water management policies
(implemented or proposed).
Since certain policies have been implemented in the basin and cannot be ignored,
it is necessary to define a scenario that considers the systems as it is actually working.
For this purpose, the Current scenario is introduced to represent the actual water
management in the Rio Grande/Rio Bravo basin, after 2004. This scenario considers: (a)
the buyback of water rights due to the PADUA program [investment of $29.5 million];
123
(b) the improvement in the infrastructure due to Minute 309 [investment of $189 million]
(delivering the water savings each December and January) and (c) the reduction in the
water allocation for Water Master Section users in the U.S., no investment considered.
The total investment estimated for the current scenario is $218.5 million [$2,753 million
pesos, monetary exchange 12.6 pesos per dollar].
Based on chapter seven results (Baseline Vs Basic Scenarios) and including the
policies already implemented in the actual water management of the basin (Current
scenario), two meta-scenarios are proposed:
 Meta-scenario A – This meta-scenario considers immediate actions to
improve the water management in the basin. It must be considered as
policies that will provide immediate benefits for the Rio Grande/Rio
Bravo basin. In the upper basin, Meta-scenario A considers the
combination of the PADUA program (a policy already implemented)
coupled with the groundwater banking (I + II) [no investment defined]. In
addition, it considers the delivery of the water savings due to Minute 309
(a policy already implemented) in an environmental pattern (III + IV) [no
investment considered because the water saved in Minute 309 is delivered
in an environmental pattern]. For the lower basin, it considers the
reduction in the water demand of Water Master Sections ( V(LRGV), a
policy already implemented ) plus buyback of water rights in DR-025
Bajo Rio Bravo (I(LRGV) [investment: $21.7 million]. The estimated cost
for Meta-scenario A is $21.7 million [$273 million pesos, monetary
exchange 12.6 pesos per dollar].
124
 Meta-Scenario B – This meta-scenario consider short term actions to
improve the water management in the basin. It must be seen as a set of
additional policies of Meta-Scenario A that will extend benefits for water
users, treaty obligations and the environment. This meta-scenario is
identical to Meta-Scenario A plus the addition in the upper basin of the
buyback of water rights until it reduces the agriculture area of DR-005
Delicias to 50,000 ha [investment: $89 million]. For the lower basin, this
meta-scenario considers the improvement in infrastructure of DR-025
Bajo Rio Bravo sharing the water savings with WMS 8-13 [investment:
$209 million]. The estimated additional cost of Meta-scenario B is $298
million [$3,755 million pesos, monetary exchange 12.6 pesos per dollar].
Table 8-1 describes Baseline scenario and the policies considered for Current
scenario, Meta-scenario A and Meta-scenario B.
125
Table 8-1: Meta-scenarios for the Rio Grande/Rio Bravo Basin
Meta-Scenario
Baseline
Upper Basin
Lower Basin (LRGV)
Water management before any policy was implemented (<2004). For the U.S. water
rights are 70% of the full allocation demand and for Mexico is the demand in 2004.
Water management after three policies were implemented in the basin: Buyback of
water rights due to the PADUA program, improvement in infrastructure due to
Minute 309 and the reduction in the WMS demand from 70% to 62%. This policy can
be seen as the current conditions of the basin. This scenario considers:
Current
I – Buyback of water rights (PADUA).
III - Improvement in infrastructure due to
Minute 309. The water savings are
conveyed to the Rio Grande each
December and January.
V(LRGV)- Reduction of WMS 8-13
demand from 70% to 62%.
Proposed water management considering immediate actions to improve the water
management in the basin, including the environment as a user into the basin. This
Meta-scenario considers:
A
I + II - Buy Back of water rights
(PADUA) plus groundwater banking
in DR-005 Delicias.
III+IV - Improvement in infrastructure
(Minute 309) in DR-005 plus savings
delivery in an environmental pattern.
I(LRGV) - Buy Back of water rights
in DR-025.
V(LRGV)- Reduction of WMS 8-13
demand from 70% to 62%.
Proposed water management considering short term actions to mitigate the worsening
from the Current scenario and to include the environment as a user into the basin.
This Meta-scenario considers:
B
I + II - Buy Back of water rights
(Reduction of DR-005 to 50,000 ha)
plus groundwater banking in DR-005
Delicias.
III+IV - Improvement in infrastructure
(Minute 309) in DR-005 plus savings
delivery in an environmental pattern.
I(LRGV) - Buy Back of water rights
in DR-025.
III (LRGV) Shared - Improvement in
the infrastructure of DR-025 and
sharing of the savings with WMS
8-13.
V(LRGV)- Reduction of WMS 8-13
demand from 70% to 62%.
Meta-Scenario A is integrated with policies that can be implemented immediately,
with a low initial cost. In the upper basin, Meta-scenario A includes the PADUA program
126
(a policy already implemented) coupled with the groundwater banking, a proposed policy
that can be implemented immediately by organizing surface and groundwater users. The
infrastructure of irrigation district DR-005 Delicias is ready, in most of the modules, to
supply surface and groundwater user with water from the reservoirs (Caballero 2005).
For this policy is strongly recommended to determine the hydraulic characteristics of the
Meoqui aquifer (storage capacity, hydraulic conductivity, recharge, surface-groundwater
interaction, maximum recovery), and then, estimate the expansion of the groundwater
pumping and its cost. In addition, it considers the delivery of the water savings due to
Minute 309 (a policy already implemented) in an environmental pattern. In this case, it is
necessary that authorities agree to change the delivery pattern from an arbitrary
December-January schedule to an environmental pattern delivery. For the lower basin it
considers the reduction in the water demand of Water Master Sections (WMS) (a policy
already implemented) plus buyback of water rights in DR-025 Bajo Rio Bravo. For DR025 Bajo Rio Bravo, the water rights bought back should come from irrigated areas with
salinity problems that have a low or none production (Zatarain et al. 2005), this policy
may take two to three years for its completion, based on DR-005 PADUA’s program.
Meta-Scenario B is integrated with policies that can be implemented in the short
term with a higher initial investment. In the upper basin, Meta-scenario B considers the
reduction in the agriculture area of DR-005 Delicias to 50,000 hectare. Data from
CONAGUA (2003 and 2009) show this reduction is reasonable: 1) the average irrigated
area is estimated of 49,574 ha. (CONAGUA 2003), and 2) the irrigated area in 2008, an
average year, was 52,323 hectare (CONAGUA 2009). The objective of this policy is to
retire from the system “paper water rights” that are not frequently supplied, only during
wet years; and also to compensate farmers that have this “paper water rights” and who
usually do not receive this water. This policy is recommended to be implemented after
127
the buyback of water rights in DR-025 for the following reasons: a) economic reasons, it
would be very difficult for the Mexican federal government to invest money to buy back
water rights from DR-025 Bajo Rio Bravo and DR-005 Delicias at the same time, and b)
political reasons, DR-005 has already been benefited with a buyback program (PADUA),
it would be politically correct to benefit other irrigation districts, such as DR-025 Bajo
Rio Bravo, before buying back water rights in DR-005 Delicias once again. For the lower
basin, Meta-scenario B considers the improvement in infrastructure of DR-025 Bajo Rio
Bravo sharing the water savings with WMS 8-13 (WMS 8-13). Considering the
significant amount of investment necessary to improve the infrastructure, $209 million,
this policy proposes sharing the cost and benefits between both irrigation districts, DR025 Bajo Rio Bravo and WMS 8-13.
8.2 RESULTS BY USER
Similarly to the previous section, results for selected water users are presented to
evaluate and verify that the policies proposed in the meta-scenarios improve the water
management for each water user.
8.2.1 DR-005 Delicias, DR-025 Bajo Rio Bravo and WMS 8-13
Table 8-2 and Figure 8-1 show the results for the Baseline, Current and Metascenario A and B for irrigations districts: DR-005 Delicias, DR-025 Bajo Rio Bravo and
Water Master Section 8-13 (WMS 8-13).
For DR-005 Delicias, results show the water management got worse from the
Baseline to the Current scenario, which means that the policies already implemented
negatively affected the water supply for this user. The water supply in Meta-scenario A
128
improves with respect to the Current scenario even though both scenarios have the same
water demand. Two policies make the difference to obtain these results: the groundwater
banking policy in the Meoqui aquifer and the delivery of the water savings of Minute 309
in an environmental pattern. Furthermore, reducing the agriculture area of DR-005
Delicias from 90,000 to 50,000 hectare increases the water sustainability for this user in
Meta-scenario B.
For DR-025 Bajo Rio Bravo, the water management slightly improves from the
Baseline to the Current scenario, from 48% to 50%. In Meta-scenario A, where its water
demand is reduced, the water supply improves from 50% to 56%, with respect to the
Current scenario. Even though the water savings due to the improvement of infrastructure
promoted in Meta-scenario B are shared with WMS 8-13, its water supply improves
significantly from 50% in the Current scenario to 62% in Meta-scenario B.
Table 8-2: Sustainability Index for DR-005, DR-025 and WMS 8-13; Baseline, Current
and Meta-scenarios
Water
User
DR-005
DR-025
WMS 813
Demand
6
Sustainability
Scenario
3
(1X10 m /year)
(%)
Baseline
1131
21%
Current
681
10%
MS-A
681
24%
MS-B
419
57%
Baseline
861
48%
Current
861
50%
MS-A
761
56%
MS-B
514
62%
Baseline
1261
32%
Current
1117
43%
MS-A
1117
43%
MS-B
1117
49%
129
62%
57%
56%
48%
50%
50%
40%
30%
20%
49%
43%
43%
MS-A
60%
Current
Sustainability Index (%)
70%
32%
24%
21%
10%
10%
DR-005
DR-025
MS-B
Baseline
MS-B
MS-A
Current
Baseline
MS-B
MS-A
Current
Baseline
0%
WMS 8-13
Figure 8-1: Sustainability Index for DR-005, DR-025 and WMS 8-13; Baseline, Current
and Meta-scenarios
For WMS 8-13, water management improves from 32% in the Baseline to 43% in
the Current scenario. Meta-scenario A does not provide any benefits for this water user,
conserving the sustainability index at 43%, with respect to the Current scenario. The
sharing of the water savings, due to the improvement of infrastructure promoted in Metascenario B, improves the water sustainability for this user from 43% in the Current
scenario to 49% in Meta-scenario B.
In summary, for the Current scenario, mixing results are obtained. Meanwhile,
this scenario improves the water management for DR-025, it does not make any change
for WMS 8-13 and it negatively affect DR-005. On the contrary, results from Metascenarios A and B improves the water management for any of these water users.
130
8.2.2 Treaty Obligations
For the treaty obligations, water management improves from 51% in the Baseline
to 68% in the Current scenario (Table 8-3 and Figure 8-2). Meta-scenario A slightly
reduces the water management for this international obligation, from 68% in the Current
scenario to 64% in Meta-scenario A. Performance criteria results of the treaty obligations
show that the vulnerability and standard deviation decreases, which is a good sign, and
also the reliability does not decrease, another good sign, but the resilience decrease and as
a consequence, the sustainability slightly decrease. Similarly, Meta-scenario B slightly
reduces the treaty obligations, from 68% in the Current scenario to 66% in Meta-scenario
B. In this case reliability increases and resilience does not decrease, but the vulnerability
and standard deviation increase and thus the sustainability index slightly decrease.
Table 8-3: Sustainability Index for Treaty Obligations; Baseline, Current and Metascenarios
Water
User
Treaty
Obligations
Demand
Sustainability
Scenario
(1X106 m3/Cycle)
(%)
Baseline
2159
51%
Current
2159
68%
MS-A
2159
64%
MS-B
2159
66%
131
64%
66%
MS-A
MS-B
68%
70%
60%
51%
50%
Current
40%
Baseline
Sustainability Index (%)
80%
Treaty Obligations
Figure 8-2:
Sustainability Index for Treaty Obligations; Baseline, Current and Metascenarios
8.2.3 Environment
Table 8-4 and Figure 8-3 show the results for all the environmental control points
evaluated in the Environmental flow policy: VM1 Cuchillo Parado, VM2 Potrero, VM3
Estación Conchos, VMc Camargo, and VMd C. Ortiz. For environmental control points
VM1, VM2, VM3 and VMd, their water supply get worse in the Current conditions with
respect to the Baseline scenario. For VMc, the environmental water supply improves
from the Baseline to the Current scenario. For Meta-scenario A, the water supply
improves in all the environmental control points, with respect to the Current scenario.
Moreover, in Meta-scenario B the water sustainability improves more, with respect of
Current and Meta-scenario A.
132
Table 8-4: Sustainability Index for Environmental Control points; Baseline, Current and
Meta-scenarios
Control
Point
VM 1
VM 2
VM 3
VMc
VM d
Scenario
Demand
(1X106 m3/year)
Sustainability
(%)
Baseline
208
61%
Current
319
41%
MS-A
292
100%
MS-B
353
100%
Baseline
174
81%
Current
270
61%
MS-A
246
100%
MS-B
299
100%
Baseline
20
81%
Current
24
79%
MS-A
23
100%
MS-B
26
100%
Baseline
23
25%
Current
23
44%
MS-A
23
75%
MS-B
23
75%
Baseline
52
31%
Current
57
30%
MS-A
56
59%
MS-B
59
76%
133
100% 100%
Sustainability Index (%)
100%
60%
81% 79%
81%
80%
100% 100%
100% 100%
61%
61%
59%
44%
41%
40%
76%
75% 75%
31% 30%
25%
20%
VM 1
Figure 8-3:
VM 2
VM 3
VMc
MS-B
MS-A
Current
Baseline
MS-B
MS-A
Current
Baseline
MS-B
MS-A
Current
Baseline
MS-B
MS-A
Current
Baseline
MS-B
MS-A
Current
Baseline
0%
VM d
Sustainability Index for all environmental control points in the Conchos
basin; Baseline, Current and Meta-scenarios
8.3 RESULTS BY GROUP
The relative sustainability results of the four water user’s groups are presented:
1. Rio Grande/Rio Bravo,
2. United States,
3. Mexico, and
4. Environment
134
8.3.1 Rio Grande/Rio Bravo
The relative sustainability index of the Rio Grande/Rio Bravo for the Baseline,
Current and Meta-scenario A and B is shown in Figure 8-4. The relative sustainability
index of the Rio Grande/Rio Bravo considers all water users for both countries, the treaty
obligations of water delivery from Mexico to the U.S., and all the environmental
requirements in the Rio Conchos Basin, the water management in the Current scenario
has improved with respect of the Baseline scenario, from 40% to 47% respectively. Metascenario A improves the water management from 47% in the Current scenario to 50% in
Meta-scenario A. Moreover, the policies promoted in Meta-scenario B improve the water
management from 47% in the Current scenario to 55% in Meta-scenario B. In summary,
the policies implemented in the Current scenario and the policies proposed in Metascenario A and B policies improve the water management in the Rio Grande/Rio Bravo
60%
55%
40%
50%
47%
50%
40%
Figure 8-4:
MS-B
MS-A
Current
30%
Baseline
Relative Sustainability (%)
basin.
Relative Sustainability for the Rio Grande/Rio Bravo group; Baseline,
Current and Meta-scenarios
135
8.3.2 United States and Mexico
The relative sustainability index of the United States and Mexico’s group for the
Baseline, Current and Meta-scenario A and B is shown in Figure 8-5. For both groups the
Current scenario improves the water management with respect of the Baseline scenario
from 33% to 42% for the U.S and from 42% to 49% for Mexico. Even though in Metascenario A is considered the delivery of water for environmental purposes, the water
management in both countries is not affected because the relative sustainability is the
same for Current and Meta-scenario A. This means that the environment can be included
into the water management without worsening the actual water supply for both countries.
Meta-scenario B further improves the water management for both countries.
42%
MS-A
44%
49%
49%
MS-A
42%
Current
50%
Current
55%
42%
40%
33%
30%
United States
Figure 8-5:
MS-B
Baseline
MS-B
20%
Baseline
Relative Sustainability (%)
60%
Mexico
Relative Sustainability for the United States and Mexico water users’
group; Baseline, Current and Meta-scenarios
136
8.3.3 Environment
The relative sustainability index of the Environmental requirements group for the
Baseline, Current and Meta-scenario A and B is shown in Figure 8-6. Results show that
the current policy is worsening the water supply for the environment, from 56% in the
Baseline to 49% in the Current scenario. The delivery of the water savings due to Minute
309 in an environmental pattern considered in Meta-scenario A significantly improve the
environmental flows in the Rio Conchos basin, from 49% in the Current scenario to 95%
in Meta-scenario A. Similarly, Meta-scenario B provides more benefits for the
95%
97%
MS-B
Relative Sustainability (%)
100%
MS-A
environment than the Current conditions.
90%
80%
70%
60%
56%
49%
50%
Current
Baseline
40%
Environment
Figure 8-6:
Relative Sustainability for Environmental requirements group; Baseline,
Current and Meta-scenarios
137
8.4 RESULTS BY REGION
In order to identify stressed water resources areas, water users have been grouped
according to their location in the basin. The relative sustainability for 13 regions (6 in the
U.S and 7 in Mexico) has been calculated using equations 3-15 and 3-16. Results of each
scenario are compared in order to identify regions where the water management
improved or got worse. This comparison is quantified by calculating the differences in
the relative sustainability ( Δ Rel. Sust.); positive numbers represent an improvement in
the water management; on the contrary, negative numbers represent draw backs in the
water management.
8.4.1 Baseline and Current Scenarios
Table 8-5 shows the relative sustainability and its change of the 13 regions for
Baseline and Current scenarios. Table 8-6 summarizes the relative sustainability by
group for Baseline and Current scenarios. Figure 8-7 shows the relative sustainability by
region for the Baseline scenario.
Table 8-5: Relative Sustainability per region; Baseline and Current scenarios
Region
US - 1
US - 2
US - 3
US - 4
US - 5
US - 6
MX - 1
MX - 2
MX - 3
MX - 4
MX - 5
MX - 6
MX - 7
Name
Forgotten River
Big Bend reach
Pecos river
Devils River
Amistad - Falcon
Lower Rio Grande Valley
Cd. Juarez - Ojinaga
Rio Conchos
Ojinaga - Amistad
Rio Salado
Amistad - Falcon
Rio San Juan and Alamos
Bajo Rio Bravo
138
Rel. Sust. (%)
Baseline
Current
8
8
100
100
29
29
100
100
46
58
38
52
38
38
27
23
100
100
26
26
71
72
33
33
55
56
Δ Rel. Sust.
(%)
0
0
0
0
+ 12
+ 14
0
-4
0
0
+1
0
+1
Table 8-6: Change in the Sustainability per group; Baseline and Current scenarios
Rel. Sust. (%)
Δ Rel. Sust.
Group
Baseline
Current
(%)
Rio Grande/Rio Bravo
40
47
+7
United States
Mexico
Treaty Obligations
33
42
51
42
49
68
+9
+7
+ 17
Environment
56
49
-7
Figure 8-7: Relative Sustainability for regions; Baseline scenario
Figure 8-7 shows the relative sustainability for the Baseline scenario, which
represents the water management before any policy was implemented in the basin
(<2004). With this display of results is possible to identify regions at risk where water
139
management must be improved. For the U.S., the Forgotten River (US-1), Pecos (US-3),
Lower Rio Grande Valley (US-6) and Amistad-Falcon (US-5) are the areas with the
lowest relative sustainability indices. For Mexico, the Rio Salado (MX-4), Rio Conchos
(MX-2), Rio San Juan (MX-6) and Cd. Juarez-Ojinaga (MX-1) are the areas with the
lowest relative sustainability indices.
Figure 8-8 shows the change in the relative sustainability (Δ Rel. Sust.) of the
Current scenario, compared to the Baseline scenario. This figure shows the regions where
the water management have been improved, remaining the same or worsen, due to the
policies implemented in the Current scenario.
Figure 8-8: Change in the Relative Sustainability, Current Vs. Baseline scenario
140
For the U.S., the water management policies implemented in the Current scenario
improved the water management for U.S. water users by 9% (from 33% to 42%), with
regional benefits in Amistad-Falcon (US-5) region by 12% and the Lower Rio Grande
Valley (US-6) by 14%. The reduction in the water allocation from 70% to 62% for water
users other than domestic, municipal or industrial, improved the water management of the
basin. In addition the improvement in the delivery of Treaty Obligations by 17% also
benefited the water management for these areas. More water was available and the water
demand was lower than in the baseline scenario.
For Mexico, the water management improved by 7% (from 42% to 49%), with
mixing results. Meanwhile the treaty obligations improved by 17% (from 51% to 68%)
and water management in regions Amistad-Falcon (MX-5) and Bajo Rio Bravo (MX-7)
slightly improved by 1%in each region; the water management in the Rio Conchos subbasin (MX-2) got worse by 4%. The policies already implemented in Rio Conchos subbasin have improved water users downstream this basin and the treaty obligations but it
has worsen the water supply in this sub-basin.
For the environment, the conditions got worse than the Baseline scenario, with a
reduction in the relative sustainability of 7% (from 56% to 49%) in this water group. The
policies implemented in the Rio Conchos aggravate the already threatened environmental
conditions in this sub-basin.
In general, considering water users of both countries, international obligations and
the environment, the Current scenario improves the water management by 7% (from 40%
to 47%), compared with the Baseline scenarios.
141
8.4.2 Meta-Scenarios
Table 8-7 shows the relative sustainability and its change (Δ Rel. Sust.) of the 13
regions for Current, Meta-scenarios A and B. Table 8-8 summarizes the relative
sustainability by group for Current, Meta-scenarios A and B. Figure 8-9 shows the
relative sustainability by region for the Current scenario.
Table 8-7: Relative Sustainability per region; Current and Meta-scenarios
Relative Sust. (%)
Δ Rel. Sust.
Region
Name
Current
MS - A
MS - B
MS - A
MS - B
US - 1
Forgotten River
8
8
8
0
0
US - 2
US - 3
US - 4
US - 5
US - 6
MX - 1
MX - 2
MX - 3
MX - 4
MX - 5
MX - 6
Big Bend reach
Pecos river
Devils River
Amistad - Falcon
Lower Rio Grande Valley
Cd. Juarez - Ojinaga
Rio Conchos
Ojinaga - Amistad
Rio Salado
Amistad - Falcon
Rio San Juan and Alamo
100
29
100
58
52
38
23
100
26
72
33
100
29
100
58
52
38
30
100
26
72
33
100
29
100
61
56
38
49
100
26
77
33
0
0
0
0
0
0
0
0
0
+7
0
0
0
0
+ 26
0
0
MX - 7
Bajo Rio Bravo
56
61
69
+5
+ 13
+3
+4
0
+5
0
Table 8-8: Change in the Sustainability per group; Current and Meta-scenarios
Rel. Sust. (%)
Group
Δ Rel. Sust. (%)
Current
MS - A
MS - B
MS - A
MS - B
Rio Grande/Rio
Bravo
United States
Mexico
Treaty Obligations
47
50
55
+3
+8
42
49
68
42
49
64
44
55
66
0
0
-4
+2
+6
-2
Environment
49
95
97
+ 46
+ 48
142
Figure 8-9: Relative Sustainability for regions; Current Scenario
Figure 8-9 shows the relative sustainability for the Current scenario, which
represents the systems in its actual conditions with the current water management
(>2004). Results from the Current scenario are used as a point of comparison for Metascenarios A and B. Notice that in both of the countries, the same regions are at risk in the
Current scenario with respect to the Baseline scenario.
Along the border, three areas are of particular interest because of their complex
water management: the Forgotten River (US-1/MX-1), the Big Bend area (US-2/MX-3),
and the Lower Rio Grande Valley (US-6/MX-7). The forgotten river sub-basin (US1/MX-1) is the most stressed area in the basin, the growing water demand for municipal
and industrial use in El Paso-Cd. Juarez plus the agriculture use of El Paso Water
143
Irrigation District #1 (EPWID #1) in Texas and DR-009 Valle de Juarez in Mexico have
exhausted the water resources in the area; the water demands are larger than the natural
availability of water. In the U.S., the system is so stressed that water planning includes:
conjunctive use of surface-groundwater, harvesting of rainwater, recharge of groundwater
with treated surface water, treatment and re-use of agricultural drain water, leasing of
water permits, water desalination systems, among other policies (TWDB 2010.a, b and
c.). In Mexico, the system is so tight, that agriculture water rights have been transferred
to the municipality of Ciudad Juarez and the wastewater treated from this city is now
used for agriculture purposes (CONAGUA 2004). These conditions are captured in the
results with a sustainability index of 8% for the US-1 and 38% for MX-1.
After the forgotten river, the Lower Rio Grande Valley (US-6/MX-7) is the most
stressed area along the border; water supply in this region depends on the water use in the
whole basin. Water management in the tributaries consumes the water that is produced
before it reaches the Rio Grande/Rio Bravo main stream. The water supply of the Lower
Rio Grande Valley depends on the storage of the international reservoirs, which depend
on the water from the tributaries. During drought periods, almost no water flows to the
Rio Grande/Rio Bravo from the tributaries, storage in both international reservoirs is
greatly decreased and the water supply for this area is threatened. For the Current
scenario, the sustainability index for MX-7 and US-6 are 56% and 52%, respectively.
The Big Bend region (US-2/MX-3) is an environmental stressed area. Even
thought the relative sustainability is 100%, this calculation does not consider the
environmental needs for this region; the environmental flows for the Big Bend reach have
not been defined yet. In addition, most of the water in the Big Bend area comes from the
Rio Conchos (75% on average) and is managed by CONAGUA, who do not have a
defined policy to deliver water from the Rio Conchos to the Rio Grande/Rio Bravo; the
144
water management in this area is uncertain. An international team has been working to
define the environmental flows along this reach (WWF 2006; Sandoval-Solis and
McKinney 2009); as well as a policy to provide environmental flows to the Big Bend
reach. There is evidence that environmental degradation has happened (Dean and
Schmidt 2011), and it is highly possible that this degradation will continue in the future if
no action is taken; thus, the environment conditions in this area are highly threatened.
In addition Figure 8-9 shows four sub-basins with a stressed water management:
Pecos (US-3), Rio Salado (MX-4), Rio Conchos (MX-2) and Rio San Juan (MX-6). In
these four sub-basins, the water demand is larger than the natural availability of water
(CONAGUA 2008.b), the water resources are over-allocated. This problematic is
aggravated with the high variability of water resources.
Figure 8-10: Change in the Relative Sustainability, Meta-scenario A Vs. Current Scenario
145
Figure 8-10 shows the change in the relative sustainability of the Meta-scenario
A, compared to the Current scenario. This figure shows the regions where the water
management have been improved, remaining the same or worsen, due to the policies
implemented in the Meta-scenario A.
For the U.S. and Mexico, the water management policies implemented in Metascenario A do not affect their water management even though policies are implemented
to deliver water to the environment. This is an important result since environmental
requirements have always been neglected or not considered because they are thought to
harm anthropogenic water users. These results prove the opposite, at least for the
environmental requirement in the Rio Conchos sub-basin. The delivery of the water
savings due to Minute 309 in an environmental patter improves the environment by 46%
with respect to the Current scenario. This is a significant improvement from a relative
sustainability of 49% in the Current scenario to 95% in Meta-scenario A. In the U.S., no
region is harmed with the policies implemented in Meta-scenario A. For Mexico, in the
upper basin, the groundwater banking policy coupled with the buyback of water rights
improved the water management in the Rio Conchos sub-basin (MX-2) by 7%. In the
lower basin, the buyback of water rights in DR-025 improved the water management of
the Bajo Rio Bravo region (MX-7) by 5%. For the treaty obligations, its sustainability
index slightly decreases by 4%. In Meta-scenario A the reliability increased and the
Vulnerability and the Standard Deviation decreased with respect to the Current scenario;
however, the resilience slightly decreased and this is the reason why the sustainability
index slightly decreases by 4%. In summary, considering water users of both countries,
international obligations and the environment, Meta-scenario A improves the water
management by 3% (from 47% to 50%).
146
Figure 8-11: Change in the Relative Sustainability, Meta-scenario B Vs. Current Scenario
Figure 8-11 shows the change in the relative sustainability of the Meta-scenario
B, compared to the Current scenario. This figure shows the regions where the water
management have been improved, remaining the same or worsen, due to the policies
implemented in the Meta-scenario B.
For the U.S., the policies proposed in Meta-scenario B improved the water
management 2% (from 42% to 44%) with respect to the Current scenario. Sharing the
water savings due to the infrastructure improvements in DR-0025 Bajo Rio Bravo with
WMS 8-13 improved the water management in Amistad-Falcon region (US-5) by 3% and
in the Lower Rio Grande Valley (US-6) by 4%. For Mexico, Meta-scenario B improved
the water management by 6% (from 49% to 55%), with respect to the Current scenario.
The improvement in the infrastructure coupled with the reduction in water rights of DR147
025 Bajo Rio Bravo increased the relative sustainability of the Bajo Rio Bravo region
(MX-7) by 13% and the Amistad-Falcon region (MX-5) by 5%. Also, the combination of
the groundwater banking policy with the reduction of the agriculture area of DR-005
Delicias from 90,000 ha to 50,000 ha improved the water demand in the Rio Conchos
sub-basin (MX-2) by 26%. This results shows how over-allocated are the agriculture
water rights in the Rio Conchos sub-basin. Similarly to the previous meta-scenario,
results for the environment show an important increase in its relative sustainability of
48% (from 49% to 97%). The delivery of the water savings due to Minute 309 in an
environmental pattern significantly improves the environmental conditions in the Rio
Conchos sub-basin. For the treaty obligations, the sustainability index slightly decreases
by 2%; practically, the sustainability is the same than in the Current conditions.
In summary, considering water users of both countries, international obligations
and the environment, Meta-scenario B improves the water management of the Rio
Grande/Rio Bravo by 8% (from 47% to 55%).
8.5 SUMMARY OF RESULTS
This section evaluates the results of the Current, Meta-scenario A and B.

Current scenario – The comparison of the Baseline and Current
scenario shows mixing results. Meanwhile the Current policies have
improved the water management for several water users (DR-025, WMS
8-13, Treaty obligations) and regions (US-5, US-6, MX-5 and MX-7), it
also has decreased the water supply for important users, such as DR-005
Delicias, and it has worsen the environmental conditions in the Rio
Conchos sub-basin. The policies implemented in Minute 309 improves the
148
water management for the treaty obligations, water users in the lower
basin (Water Master Sections and DR-025); but paradoxically, this policy
worse the water supply for DR-005 Delicias and the environment. These
negative effects are stronger than the improvements obtained because of
the buy backs of water rights due to the PADUA program. In contrast, the
reduction in the full allocation demand for U.S. water users from 70% to
62% significantly improved the water management for the U.S. Even
though on the overall Current scenario results shows an improvement in
the water management of the Rio Grande/Rio Bravo by 6%, compared
with the Baseline scenario, the policies implemented in this scenario
worsen the water management for important users, regions and the
environment.

Meta-scenario A – The comparison of Meta-scenario A and
Current scenario shows improvements in the water management. The
policies proposed in Meta-scenario A do not affect the water management
in the U.S. and Mexico meanwhile it significantly improves the water
supply for environmental purposes, by 46%. The policies proposed in
Meta-scenario A can be applied immediately to provide benefits to water
users, such as the groundwater bank policy for DR-005 Delicias; to the
environment, such as the delivery of the water saved in Minute 309 in an
environmental pattern, and other policies are meant to obtain benefits
given the characteristics of the user, for instance buying back water rights
in DR-025 to retire water rights from irrigated areas with salinity
problems. The proposed policies coupled with the already implemented
improve the water management in the Rio Grande/Rio Bravo basin. Meta149
scenario A also shows that an environmental water management policy
can be applied without harming human water users. This is an important
result since environmental requirements have always been neglected or
not considered because they are thought to harm anthropogenic water
users. In this scenario water users located in the Rio Conchos sub-basin
and the Bajo Rio Bravo region are benefited. The treaty obligations
slightly decrease its performance by 4%. The overall improvements
estimated for the Rio Grande/Rio Bravo are 3%, with respect to the
Current scenario.

Meta-scenario B – The comparison of Meta-scenario B and
Current scenario shows significant improvements in the water
management. The policies proposed in Meta-scenario B are strategies with
higher initial investment that can be applied in the short term. These
policies are intended to share benefits and investment, such as the
improvement in infrastructure in DR-025 Bajo Rio Bravo and the sharing
of the investment and the water saved between DR-025 Bajo Rio Bravo
and WMS 8-13; or policies intended to compensate water users by retiring
from the system water rights that are not frequently supplied, such as the
reduction in the irrigated area of DR-005 Delicias from 90,000 to 50,000
hectare. The policies proposed in Meta-scenario B improve the water
management in the U.S. and Mexico by 2% and 6%, respectively. Results
show an increment in the environmental relative sustainability of 48%.
This scenario significantly improves the water supply for environmental
purposes. Again, this policy shows that an environmental water
management policy can be applied without harming anthropogenic water
150
users. Water users located in the Rio Conchos (MX-2), Bajo Rio Bravo
(MX-7), Amistad Falcon (US-5 and MX-5) and Lower Rio Grande Valley
(US-6) regions are benefited in their water supply. Practically the
performance of the treaty obligations is the same as in the Current
scenario, with a slight decrease of 2%. The overall improvements of Metascenario B estimated for the Rio Grande/Rio Bravo are 8%, with respect to
the Current scenario.
Meta-scenario A and B provide benefits to water users from Mexico, the U.S. and
the environment. However, both scenarios slightly decrease the water management of
Treaty obligations, from a sustainability index of 68% in the Current scenario, to a
sustainability index of 64% and 66% in Meta-scenario A and B, respectively. This might
be an issue to overcome, considering that authorities from both countries have discussed
about improving the delivery of water for treaty obligations because of the water debt in
cycles 25 and 26 (1992-2002). Recent research has shown that a risk analysis and drought
forecasting can improve the delivery of Treaty obligations (Sandoval-Solis and
McKinney 2010). Further research is necessary to define and include a drought
forecasting policy for Treaty Obligations.
151
Chapter 9 Conclusions
9.1 AIM OF THE DISSERTATION
The objectives of this dissertation are:
1.
Construct, calibrate and validate a water resources planning model that represents
the hydro-physical and regulatory framework of a large-scale transboundary
basin.
2.
Define a methodology to evaluate and compare different scenarios of water
management policies.
3.
Utilize the water resources planning model and the methodology defined to
evaluate different scenarios for improving water management in the basin.
4.
Assess the water planning and management for the transboundary basin.
9.2 DISCUSSION
A hydrologic water planning model for the large scale transboundary Rio
Grande/Rio Bravo basin was built using the Water Evaluation and Planning System
(WEAP) software. The Rio Grande/Rio Bravo WEAP model represents the water
management in the basin; for U.S. water demands it follows the water allocation of the
Texas Rio Grande Water Master Program; for Mexican water demands it follows the
water allocation according to the Mexican National Water Law and between both
countries, it follows the Convention of 1906 and the Treaty of 1944. The model has a
total 216 water demands, including surface and groundwater rights, accounting for a total
annual demand of 12,679 million m3. The characteristics and operation of 25 reservoirs
have been included in the model. The total storage capacity of the modeled reservoirs is
152
approximately 26,300 million m3. A total of 21 headflows and 22 incremental inflows
along the reaches are included in the Rio Grande/Rio Bravo WEAP model. The model
contains channel loss factors for the river reaches accounting for conveyance,
evaporation, evapotranspiration and seepage losses.
Although the model contains inflow data for sixty years, the Rio Grande/Rio
Bravo WEAP model has been calibrated for 15 years, from October 1978 to September
1993. This period is selected because most of the basin infrastructure was complete by
then and sufficient historical water supply information exists for most of the water
demands. In general, two important sets of parameters were used to calibrate the Rio
Grande/Rio Bravo WEAP model: the conveyance losses along the streams and the rules
governing the release of water from the conservation pools of the dams.
A Historic scenario was developed to evaluate the accuracy of the model; results
from the model were compared to historical values for reservoir storage and gauged
stream flow. During the calibration and validation process, the storage in the international
reservoirs Amistad and Falcon were used as indicators to evaluate the performance of the
model because: (a) they store the water for each country according to the treaty of 1944;
and (b) both reservoirs are influenced by the water management in the entire basin. Two
measures were used to evaluate the goodness of fit of the storage in the international
reservoirs for each country: the coefficient of efficiency and the coefficient of agreement.
These coefficients compare the observed values to the model predicted monthly values.
The coefficient of efficiency ranges from minus infinity to 1, with higher values
indicating better agreement. The coefficients of efficiency for Mexico and the U.S. are
0.825 and 0.805, respectively; meaning that the mean square error (i.e. the squared
differences between the observed and model values) is 17.5% and 19.5% of the variance
in the observed data. This level of efficiency coefficient indicates very good performance
153
according to Moriasi et al. (2007). The index of agreement varies from 0 to 1 with higher
values indicating a better agreement between the model and the observations. The
coefficients of agreement for Mexico and the U.S. are 0.953 and 0.945, respectively;
meaning that the mean square error is 4.7% and 5.5% of the potential error. These values
indicate that the difference between the observed and predicted values (in fact, the mean
square error) is small compared to the variance or the potential error. Both coefficients
show that the Rio Grande/Bravo WEAP model is adequately representing the water
resource system; the mean square error is less than 20% of the observed variance of the
data, and less than 6% of the potential error.
A methodology has been developed in this research to compare and evaluate
alternative water management policies. First, a set of performance criteria is selected to
evaluate essential or desired qualities required in the water management for each type of
water user, the environment or system requirements. Second, results from these
performance criteria are summarized using the Sustainability Index, which is an index
that facilitates the evaluation and comparison of water management policies. Third,
Sustainability Indices for several water users are calculated using the Relative
Sustainability Index, which is an average of the former Sustainability Index weighted by
the water demand. Through this method it is possible to evaluate not only the effect of
water management policies for individual water users, but also, for groups of water users,
the environment, regions and for the whole system.
Five performance criteria are used in the Rio Grande/Rio Bravo: Reliability,
Resilience, Vulnerability, Maximum Deficit and Standard Deviation. Reliability
represents the period of time a user’s water demand is fully supplied during the period of
simulation. Resilience captures the system’s capacity to adapt to changing conditions; it
is the probability that the system recovers from a period of failure. Vulnerability and
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Maximum Deficit are the expected value of deficits and the maximum deficit for a user, if
they occur. Finally, the Standard Deviation criterion is the standard deviation of the
water supply the respective water user. The sustainability index is used to summarize
these performance criteria.
In this research the Sustainability Index proposed by Loucks (1997) was
improved, moving from a product of the performance criteria to a geometric average of
the performance criteria. This improvement preserves the original characteristics of the
Index, but it enhances the content, clarity and flexibility of the sustainability index. One
of the main advantages of the Sustainability Index is the ability to compare not only
individual water users but also environmental or system requirements. The Relative
Sustainability Index is used to summarize the Sustainability Indices. The Sustainability
Index is an Integrated Water Resources Index that summarizes the results of essential or
desired performance criteria rather than an index that address the sustainability of a
certain water user. The name of Sustainability Index has been preserved to match the
literature on the index.
Initially, eleven water management policies were evaluated in this dissertation.
These basic scenarios were divided in two groups, for the upper and lower basin.
Scenarios for the upper basin included policies already implemented such as (1) the
Mexican PADUA program of water rights buyback in irrigation districts 090 Bajo Rio
Conchos and 005 Delicias through the PADUA program, (2) improvements in the
infrastructure of DR-005 Delicias due to IBWC Minute 309; and policies proposed such
as (3) the Groundwater banking through the In Lieu method in DR-005 Delicias and (4)
the delivery of environmental flows in the Rio Conchos sub-basin. Scenarios for the
lower basin included policies already implemented such as (1) water allocation reduction
for U.S. water user along the thirteen Water Master Sections in Texas; and policies
155
proposed such as (2) buyback of water rights and (3) infrastructure improvements in
irrigation district 025 Bajo Rio Bravo.
The process of scenario’s evaluation was done in two steps (see Figure 9-1). In
the first step, each of the basic scenarios or simple combinations of these were evaluated
and compared with the Baseline scenario. The Baseline scenario is the representation of
the system before any policy was implemented (before 2004). This scenario is used to
quantify, identify and compare the benefits or negative effects of each scenario on water
users, the environment or international requirements. The comparison was done using the
Sustainability Index and the Relative Sustainability Index. For the upper basin two
scenarios produced the most benefits for the system: (1) Scenario I + II, buyback of water
rights coupled with groundwater banking in DR-005 Delicias and (2) Scenario III + IV,
improvement in infrastructure with water savings delivered in an environmental pattern.
For the lower basin two scenarios promoted the most benefits: (1) Scenario III (LRGV)
Shared, infrastructure improvements in DR-025 Bajo Rio Bravo and sharing the water
savings with Texas Water Master Sections; and (2) Scenario I + III (LRGV), buyback of
water right and infrastructure improvements in DR-025 Bajo Rio Bravo.
In the second step, winning scenarios, called Meta-scenarios, are compared with
the Current scenario. The Current scenario is the representation of the system after
policies were implemented in the basin. Since 2004, three policies have already been
implemented in the basin: (1) Scenario I, buyback of water rights through the PADUA
program, (2) Scenario II, infrastructure improvement due to Minute 309, and (3) Scenario
V (LRGV), reduction in the water allocation for Texas Water Master Sections. Metascenarios are a combination of policies that consider the policies of the Current scenario
plus scenarios that were identified in the previous step that increase benefits for the
156
system. Two Meta-scenarios were evaluated and compared with the Current scenario:
Meta-scenario A and B.
Figure 9-1: Methodology proposed for results’ analysis
Meta-scenario A considers Scenario I + II [buyback of water rights plus
groundwater banking in DR-005 Delicias], Scenario III + IV [Minute 309 with water
savings delivered in an environmental pattern], Scenario I (LRGV) [buyback of water
rights in DR-025 Bajo Rio Bravo] and Scenario V (LRGV) [reduction of demand in
Texas Water Master Sections from 70% to 62%]. Results from Meta-scenario A show
improvements in the water management of the system, with respect to the Current
scenario. The policies proposed in Meta-scenario A do not affect the water management
in the U.S. and Mexico, but it does significantly improve the water supply for
157
environmental purposes, by 46%. The delivery of environmental flows in the Rio
Conchos sub-basin does not affect water users in the Rio Conchos sub-basin because: a)
water is equitably distributed, maintenance flows are delivered when there is enough
water in the reservoirs to fully supply the water users, and drought flows are delivered
when shortages are expected; b) the water savings of Minute 309 are delivered in an
environmental pattern; and c) there is conjunctive use of surface and groundwater, the
groundwater banking policy proposed for the Meoqui aquifer provides a more reliable
supply for DR-005. Similarly, the delivery of environmental flows in the Rio Conchos
sub-basin does not affect water users in the Lower Rio Grande Valley (LRGV), such as
DR-025 Bajo Rio Bravo or the Texas Water Master Sections, because water is captured
in the international reservoirs Amistad and Falcon, stored and redistributed according to
the necessities of water users in the LRGV. This policy shows a high likelihood that an
environmental water management policy might be applied without harming human water
users. Water users located in the Rio Conchos sub-basin and the Bajo Rio Bravo regions
benefit from this scenario. This is an important result since environmental requirements
have mostly been neglected or not considered in this region because they are thought to
harm anthropogenic water users. The overall improvements are estimated to be 3%, with
respect to the Current scenario.
Meta-scenario B is similar to Meta-scenario A with the difference that in Scenario
I + II the buyback of water rights is more extensive in order to reduce the irrigated area of
DR-005 Delicias from 90,000 ha to 50,000 ha, this reduction might be accomplished by
compensating farmers who have water rights that are difficult to supply. Meta-scenario B
also includes Scenario III (LRGV) Shared [infrastructure improvements in DR-025 and
sharing water savings with Texas Water Master Sections]. Results from Meta-scenario B
show significant improvements in the water management of the system, with respect to
158
the Current scenario and Meta-scenario A. The policies proposed in Meta-scenario B
improve water management in the U.S. and Mexico by 2% and 6% according to the
Sustainability by Group Index, respectively. Results show an increment in the relative
sustainability of the environment of 48%. The delivery of environmental flows in the Rio
Conchos sub-basin does not affect water users in the Rio Conchos sub-basin for the
reasons already explained in Meta-scenario A and because water demands in the Conchos
sub-basin have been reduced in order to retire water rights that are difficult to supply.
Water users in the LRGV are not affected by environmental flows in the Conchos basin
because the environmental flows are captured, stored and redistributed in the
international reservoirs Amistad and Falcon. This scenario significantly improves the
water supply for environmental purposes. Again, this policy shows the high likelihood
that an environmental water management policy might be applied without harming
anthropogenic water users. Under this Meta-scenario, water users in located in the Rio
Conchos, Bajo Rio Bravo, Amistad-Falcon reach and Lower Rio Grande Valley regions
benefit in their water supply. The overall improvement of Meta-scenario B is 8% with
respect to the Current scenario.
Meta-scenario A could be considered a set of immediate policies that have a high
likelihood of improving water management in the basin, mostly for the environment.
Meta-scenario B could be considered a set short term policies that have a high likelihood
of improving water management for the U.S., Mexico, and the environment. Both Metascenarios would be implemented by policies that will require decisions from authorities
and water users; Meta-scenario A and B are a set of policies suggested by the author;
however, the selection and order of these policies can change depending on the decision
making process.
159
In order to assess the water planning and management of the Rio Grande/Rio
Bravo, the development and findings of this research have been shared with water users;
NGO’s; local, state and national water authorities; researchers; academia; and people
interested in the Rio Grande/Rio Bravo basin, in both countries. I have participated in
several meetings, mostly for three purposes: (1) to learn from the water users, managers,
people who operate the system and decision makers that make the regulations and
policies; (2) to share and explain the water resources planning model built for the Rio
Grande/Rio Bravo basin; and (3) to present the results obtained with the model, and the
methodology used to summarize the results.
Two technical sessions (workshops) were conducted in order to explain in detail
the construction and algorithms inside the Rio Grande/Rio Bravo water planning model:
one at Mexican Institute of Water Technology (IMTA) in Cuernavaca Mexico in March
2009 and the other at the International Boundary and Water Commission (IBWC) in El
Paso, Texas in April 2009.
Results of the scenario analysis were presented to several authorities. In June
2009, the results were presented in the IBWC office in Ciudad Juarez, Mexico.
Authorities from both countries were presented with and discussed the simulation model
and the results obtained. In August 2009 the results of this research were presented to the
Rio Bravo Basin Council in Monterrey, Mexico. This organization regulates and
establishes the water management policies for the Rio Grande/Rio Bravo on the Mexican
side. In October 2009, results were presented to the TCEQ in their central offices at
Austin, Texas. Comments and suggestions from Carlos Rubinstein (Commissioner),
Stephen Niemeyer (Policy Analyst), Kelly Keel (Water Quality Planning Division) and
Ramiro Garcia (Border and South Central Texas Area Director) were received in this
meeting. Also, results of scenarios that improve the delivery of environmental
160
requirements were presented to several NGOs, such as World Wildlife Fund, Profauna,
The Nature Conservancy, Environmental Defense, among others. Since 2008, I have been
part of an international technical group to determine and identify a policy for
environmental flows in the Big Bend reach. On December 2009 the World Wildlife Fund
organized a field trip on the Rio Conchos with this international group. Research in this
area is still in development to determine and propose environmental flows in the Big
Bend region.
According to Loucks et al. (1981), a measure of success of any systems’ study
resides in the answer to the following questions:
(1) Did the study have a beneficial impact on the planning and decision-making
process? Yes, it did. For the planning process, the model developed in this research will
be used as the foundation for the future institutional water planning models of the basin.
For the decision making process, water users, scientists, authorities, and decision makers
are aware of the potential benefits that are possible to achieve, for whom and where, in
the immediate and short term. The current research has balanced the interests of different
groups (environmentalist, irrigators, municipalities and authorities) providing a better
understanding of the basin.
(2) Did the results of the study make the debate over the proper choice of
alternatives more informed? Yes, it did. After the campaign of presenting research results
(described above), water users, scientists, NGO’s, authorities, and decision makers of
both countries now know which policies have a high likelihood of improving or
worsening the system; the decision making process will be more informed because of the
present research.
(3) Did it introduce competitive alternatives which otherwise could not have been
considered? Yes, it did. For instance, this research provides strategies to reconcile
161
environmental and anthropogenic water requirements; this research provides evidence
that environmental water requirements can be included as an integral part of the basin
water management without harming human water users. This is an important result since
environmental requirements have tended to be neglected because: (a) they are thought to
harm human water users and/or (2) there is no water left for this purpose. This research
proves the contrary.
Based on the answers of the previous questions, the current research has been
successful in enlightening the water planning and management of the Rio Grande/Rio
Bravo basin.
9.3 CONCLUSIONS
This dissertation meets the objectives outlined at the beginning of this chapter:
1.
A water resources planning model was constructed, calibrated and validated
which represents the hydro-physical and regulatory framework of the Rio
Grande/Rio Bravo basin, a large scale transboundary basin between the United
States and Mexico. The Rio Grande/Rio Bravo WEAP model included 216
demands, 25 reservoirs, and the proper algorithms to allocate water within the
U.S., Mexico and among both countries, according to international agreements
and national and state regulations. Calibration and validation were performed for
a 15 year period. Results from the model testing show a reasonable agreement
between the results obtained from the model and the historic records.
2.
A methodology that evaluates and compares different scenarios has been defined
in this research. The essential or desired qualities for each water user,
162
environmental or system requirement were evaluated using five performance
criteria: Reliability, Resilience, Vulnerability, Maximum Deficit and Standard
Deviation. These performance criteria were summarized using the Sustainability
Index, which is an index that facilitates the evaluation and comparison of water
management policies. Furthermore, sustainability indices for several water users
were calculated using the Relative Sustainability Index, which is an average of the
sustainability index weighted by the water demand. Through this methodology it
is possible to evaluate not only the effect of water management policies for
individual water users, but also, for groups of water users, the environment,
regions and for the whole system.
3.
The water resources planning model has been used to evaluate different scenarios
in the Rio Grande/Rio Bravo basin. Initially, a set of 11 scenarios were evaluated
and compared with the Baseline scenario (which represents the system before any
scenario) in order to identify the benefits and damages for water users,
environmental and system requirements. This evaluation helped identify winning
policies that improved the water management in the basin. A set of Metascenarios (scenarios integrated of winning policies) was evaluated and compared
with the Current scenario (which represents the system after the scenarios were
implemented). Results from the Meta-scenarios showed improvements in the
water management for water users, environmental and system requirements,
immediately and in the short term.
4.
Several actions have been taken to assess the water planning and management in
the Rio Grande/Rio Bravo basin including: (1) explaining the algorithms in the
model in meetings, trainings and workshops; (2) providing the model with
documentation and training on how to use it; (3) presenting results to water users,
163
authorities, NGO’s, academia and all people interested in the water management
of the Rio Grande/Rio Bravo; (4) sharing information, findings and knowledge of
the basin; (5) promoting discussion about alternative policies to improve the water
management in the basin; and (6) being an active participant in the scientific
committee to promote environmental flows in the Big Bend area.
5.
The methodology applied in the Rio Grande/Rio Bravo can be applied to any
other basin, including transboundary basins, for any process of water management
evaluation, to determine if the policy or policies proposed improve the water
management, by how much, where, and for which performance criteria.
This dissertation defines a methodology to evaluate and compare water
management scenarios. The methodology proposed was successfully applied in the Rio
Grande/Rio Bravo transboundary basin. This methodology consists of a multistepmultilevel process. Immediate and short term policies are integrated in Meta-scenario A
and B. These policies were compared with the Current scenario and showed
improvements of 3% and 8%; respectively, with respect of the Current water
management in the whole basin.
9.4 RECOMMENDATIONS
This dissertation presents a water resources planning model to evaluate several
water management scenarios for the Rio Grande/Rio Bravo transboundary basin. The
model was calibrated for a 15 year period (Oct/1978 – Sep/1993). Two main parameters
were adjusted in the calibration process: the conveyance losses along the streams and the
rules governing the releases of water from the conservation pools of the dams. Fixed
164
values were set in the model for conveyance losses along the streams for the whole
hydrologic period of analysis; which means that the conveyance losses are the same for
the whole season and for all years. Even though this assumption proved adequate for the
calibration period (because these values are the mean conveyance losses under normal
conditions), further research is needed to determine the conveyance losses as functions of
the seasons and the hydrologic conditions (dry, normal or wet).
The objective of this research is to identify policies that can improve water
management in the basin for water users of each country, treaty obligations and the
environment. The results of this research can be used to suggest policies to authorities,
NGOs, water users; however, it was not specifically designed for this purpose. For further
insight into the policies and how they can be used to inform decision makers, please
contact the author.
9.5 FUTURE WORK
This dissertation is focused on the hydrologic feasibility of the scenarios
evaluated; quantifying if there is enough water in the system to apply the proposed
scenarios. For all of the scenarios evaluated in this dissertation, except the groundwater
banking in irrigation district 005 Delicias, there is enough economic data available to
evaluate the cost of each scenario. Further research is needed to determine the cost of
implementation and maintenance of the groundwater banking scenario in irrigation
district 005 Delicias. Once all the economic data are available, an economic analysis can
be performed for the immediate and short term policies proposed in Meta-scenario A and
B.
165
In this dissertation several scenarios were evaluated using a 60 year hydrologic
period of analysis, from Oct/1940 to Sep/2000. Even though this period contains several
droughts and wet periods, results were obtained for this unique realization of conditions.
Because of this, future research is needed to build a stochastic model that allows
evaluation of the system under different hydrologic conditions. There is enough
hydrologic data in the basin to build a stochastic model that will help evaluate water
management under different hydrologic conditions. This will help to identify risks and
weaknesses of the proposed Meta-scenarios, as well as confidence interval for the
policies.
166
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VITA
Samuel Sandoval Solis was born in Mexico City, Mexico, on August 20th, 1980,
the only son of Jesus Jorge Sandoval y Sanchez and Alicia Solano Audeves. Mr.
Sandoval has one older sister, Georgina. After graduating from high school, he started his
undergraduate studies in Civil Engineering at Instituto Politecnico Nacional (IPN) in
Mexico City. Mr. Sandoval received his Bachelor of Engineering degree from IPN in
June, 2003. In January 2003, he started his graduate studies at IPN; he received his
Master’s of Science in Hydraulics with honors in December 2005 for the thesis “Surface
Water Availability Model for the San Juan Basin”. He also was awarded first of his class
during his Master’s of Science studies. In 2006, he was awarded with a scholarship from
the Mexican Council of Science and Technology (CONACYT from his acronym in
Spanish) to make his doctoral studies in the program of Civil, Environmental and Water
Resources Engineering at The University of Texas at Austin, where he moved with his
wife Silvia in fall 2006. Since then, he has focused his research in the Rio Grande/Rio
Bravo basin, a transboundary basin between the United States and Mexico. In particular,
Mr. Sandoval has done extensive research in finding policies that would improve the
water management in the basin for water users, international obligations and the
environment. The author has accepted an Assistant Professor and Cooperative Extension
Specialist position in the department of Land, Air and Water Resources at University of
California, Davis, where he will expand his area of expertise to California.
Permanent Address: To contact the author please send a message to his permanent
email address: [email protected]
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